Screening for Cervical Cancer with High Risk Human Papillomavirus Testing: Updated Evidence Report and Systematic Review for the U.S. Preventive Services Task Force

Abstract

Importance:

Cervical cancer can be prevented with detection and treatment of precancerous cell changes caused primarily by high-risk viral types of. human papillomavirus (hrHPV), the causative agents in over 90% of cervical cancers.

Objective:

To systematically review benefits and harms of cervical cancer screening for hrHPV to inform the U.S. Preventive Services Task Force.

Data Sources:

MEDLINE, PubMed, PsycINFO, Cochrane Collaboration Registry of Controlled Trials January 2011 through February 15, 2017; surveillance through May 25, 2018.

Study Selection:

Randomized clinical trials (RCTs) and cohort studies comparing primary hrHPV screening alone or hrHPV co-testing (both hrHPV testing and cytology) to cytology (Pap test) screening alone.

Data Extraction and Synthesis:

Two investigators independently reviewed abstracts and full-text articles and quality rated included studies; data were qualitatively synthesized.

Main Outcomes and Measures:

Invasive cervical cancer; cervical intraepithelial neoplasia (CIN); false-positives, colposcopy, biopsy rates; psychological harms.

Results:

8 RCTs (n=410,556), 5 cohort studies (n=402,615), and 1 individual participant data (IPD) meta-analysis (n=176,464) were included. Trials were heterogeneous for screening interval, number of rounds, and protocol. For primary hrHPV screening, evidence was consistent across 4 trials demonstrating increased detection of CIN3+ in Round 1 (relative risk [RR] range, 1.61 [95% CI, 1.09 to 2.37] to 7.46 [95% CI, 1.02 to 54.66]). Among 4 hrHPV co-testing trials, first round CIN3+ detection was not significantly different between screening groups; cumulative CIN3+ detection over 2 screening rounds ranged from RR of 0.91 to 1.13 . In first round screening, false positive rates for primary hrHPV screening ranged from 6.6% to 7.4% compared to 2.6% to 6.5% for cytology. For co-testing false positives ranged from 5.8% to 19.9% in the first round of screening compared with 2.6% to 10.9% for cytology. First round colposcopy rates were also higher: ranging 1.2% to 7.9% for primary hrHPV testing compared to 1.1% to 3.1 % with cytology alone; co-testing colposcopy rates ranged from 6.8% to 1.9% compared with 3.3% to 5.2% for cytology alone. The IPD meta-analysis of data from 4 co-testing trials and 1 primary hrHPV screening trial found lower invasive cervical cancer risk with any hrHPV screening compared to cytology alone (pooled RR 0.60, 95% CI, 0.40 to 0.89).

Conclusions and Relevance:

Primary hrHPV screening detected higher rates of CIN3+ at first round screening compared with cytology. Co-testing trials did not show initial increased CIN3+ detection. Both hrHPV screening strategies had higher false positive and colposcopy rates than cytology, which could lead to more treatments with potential harms.

INTRODUCTION

High-risk human papillomavirus (hrHPV) is readily transmitted through sexual contact,^1,2 and is recognized as a causative agent in over 90% of cervical cancers.³ Persistent infection with hrHPV types 16 and 18 is responsible for most cases.^4,5 Although a high proportion of sexually active women become infected with some HPV type by age 25, most infections resolve spontaneously.⁶ Effective screening and treatment for precancerous lesions are associated with low rates of cervical cancer mortality in the United States.⁷ Annual age-adjusted cervical cancer incidence in the United States was 7.4 cases per 100,000 women and mortality was 2.3 deaths, per 100,000 women (2010-2014), with the highest incidence among black (8.7 per 100,000) and Hispanic (9.1 per 100,000) women. Black women also had the highest mortality rate (3.8 deaths per 100,000 women).⁸

In 2012, the U.S. Preventive Services Task Force (USPSTF) recommended screening women ages 21 to 65 for cervical cancer with cytology every 3 years, with an option for women ages 30 and older for hrHPV co-testing every 5 years (A recommendation).⁹ This systematic review was conducted to update evidence on cervical cancer screening, focused on the effectiveness of hrHPV screening strategies relative to cytology-based screening, to support an updated USPSTF recommendation.

METHODS

Scope of Review

Cytology is the foundation for longstanding cervical cancer screening recommendations with well-established benefits and harms. The USPSTF commissioned this review to evaluate direct evidence from trials and large observational cohort studies on the comparative effectiveness of screening approaches that use hrHPV screening. Specifically, the 2 key questions (KQs) (Figure 1) aimed to identify the benefits (KQ 1) and harms (KQ 2) of cervical cancer screening using hrHPV screening alone as the initial test (primary screening) or paired with cytology (co-testing) compared to screening with cytology (Pap test) as the primary test. Additional methodological details regarding the review search strategies, detailed study inclusion criteria. Excluded studies, and description of data analyses are available in the full evidence report.

Figure 1.

Analytic Framework

Refer to USPSTF Procedure Manual for interpretation of the analytic framework.⁵⁹

Data Sources and Searches

Comprehensive literature searches were performed for primary literature in MEDLINE, PubMed, PsycINFO, and the Cochrane Collaboration Registry of Controlled Trials from January 2011 through February 15, 2017, bridging from the previous USPSTF review.¹⁰ Database searches were supplemented with experts’ suggestions and by reviewing reference lists from other relevant systematic reviews. After February 2017, ongoing surveillance continued through article alerts and targeted searches of high-impact journals to identify major studies published in the interim that could affect the conclusions or understanding of the evidence and the related USPSTF recommendation. The last surveillance was conducted on May 25, 2018 and resulted in the addition of the initial results of the Compass trial.¹¹

Study Selection

Two reviewers independently reviewed 2,972 unique citations and 164 full-text articles against specified inclusion criteria (Figure 2). Discrepancies were resolved through consensus and consultation with a third investigator when required.

Figure 2.

Literature Flow Diagram

Feb, February; Jan, January, USPSTF, U.S. Preventive Services Task Force

^a One publication (Ronco 2010¹⁷) includes two trials: NTCC Phase I and NTCC Phase II, so it is counted as two publications instead of one.

^b Reasons for exclusion:

Aim: Study aim was not relevant

Setting: Study was not conducted in a country relevant to U.S. practice, or not conducted in, recruited from, or feasible for primary care or a health system

Comparative Effectiveness: Active comparator (e.g., liquid-based cytology vs. conventional cytology alone)

Outcomes: Study did not have relevant outcomes or had incomplete outcomes

Population: Study was not conducted in an included population

Intervention: Intervention was out of scope

Design: Study did not use an included design

Language: Publication not in English

Quality: Study was poor quality

Unable to Locate: Review staff was unable to locate article

Eligible studies were rated as fair or good quality, published in English, and conducted in highly developed countries.¹² Quality assessment criteria are included in the online supplement as e-Table 1. Studies had to be conducted in primary care or generalizable settings (e.g., family planning clinics); those studies based on laboratory results alone without an identified cohort were excluded. Randomized clinical trials (RCTs), individual participant data meta-analyses, systematic reviews, and large (n ≥ 10,000) longitudinal cohort studies that examined the benefits or harms of primary hrHPV screening or co-testing among average risk women aged 21 years or older were included. Studies in women without a cervix, at high-risk for cervical cancer, or who were pregnant were excluded. Studies evaluating hrHPV as a triage test following cytology compared to cytology alone were excluded. Cohort studies of less than 10,000 women were excluded, unless they addressed a subpopulation of interest (e.g., underscreened women).

Invasive cervical cancer generally develops over years, preceded by progressive precancerous changes of the cervix, defined as cervical intraepithelial neoplasia (CIN), categorized as CIN1, CIN2, and CIN3.¹³ For KQ1, because invasive cervical cancer is a rare event in countries with organized screening programs such that even large trials did not have sufficient sample size or duration to detect changes in invasive cervical cancer incidence, CIN3 or worse (CIN3+) was chosen as the primary outcome. CIN3+ was consistently reported because of broad consensus that detection and treatment of CIN3 can prevent progression to invasive cervical cancer. For KQ 2, studies reporting CIN2+ false positive or invasive cervical cancer false negative screening test results, biopsy and/or colposcopy rates, or psychological harms (e.g., labeling, stigma, distress, quality of life) were included.

Data Extraction and Quality Assessment

Two investigators independently assessed the quality of included studies using USPSTF design-specific criteria for RCTs,¹⁴ and the Newcastle-Ottawa Scale for observational studies.¹⁵ Each study was rated as good, fair, or poor (eTable 1). Disagreements in quality ratings were resolved by consensus, and consultation with a third investigator if required. Poor quality studies with major flaws (e.g., attrition > 40%, differential attrition >20%) or multiple important limitations that could invalidate the results were excluded. One investigator extracted study-level data (study design details, population and intervention characteristics, outcomes) into standardized evidence tables and a second investigator confirmed the accuracy of the data.

Data Synthesis and Analysis

Due to the heterogeneity of screening tests, screening protocols, follow-up protocols, and settings, results were qualitatively synthesized. Summary tables of study design, population characteristics, protocols, intervention and follow-up details for each round of screening were created. Results were synthesized by KQ and screening strategy, either primary hrHPV screening or co-testing. When possible, results were also stratified by age (women aged < 30-35 years vs. ≥ 30-35 years) because of lower prevalence of hrHPV in women aged 30 years or older. Results were based on a ‘number of women screened’ denominator, rather than intention-to-treat calculations using all women randomized. Relative risks (RRs) and 95% , 2-sided confidence intervals (CI) were calculated when not reported in the study. Stata version 15.1 (StataCorp LP, College Station, TX) was used for all analyses.

To estimate potential harms or burden of screening, test positivity, colposcopy and false positive rates were reported or calculated from available data. The false positive rate was reported to quantify the extent to which women in a cervical cancer screening program experienced positive screening test results necessitating further follow-up (i.e., triage testing, repeat screening, colposcopy, and biopsy), and were not found to have precancerous lesions or cervical cancer (i.e., CIN2+). This was calculated as the number with a positive screening test without diagnosis of CIN2+ as a proportion of women screened who were not diagnosed with CIN2+. This pragmatic definition relies on colposcopy as a reference standard, recognizing that there is variability in the accuracy of colposcopy and biopsy.¹⁶ False negatives were defined as the proportion of invasive cervical cancer cases occurring among women with negative preceding screening results. Psychological harms, including adverse effects on anxiety, distress, and sexual satisfaction, were abstracted when reported.

RESULTS

Effectiveness of Screening

Key Question 1. What is the effectiveness of human papillomavirus for high-risk HPV types (hrHPV) testing, with or without cytology, as a primary screening strategy for reducing cervical cancer mortality and incidence compared with currently recommended screening strategies for women in the United States?

Four fair- or good-quality cervical cancer screening RCTs were identified that compared primary hrHPV screening with cytology ( n=282,838 women) ^11,16–22 and 4 RCTs compared co-testing with cytology (n=127,717 women) (Table 1).^17,23–33 One IPD meta-analysis combined 176,464 women from 1 primary hrHPV screening trial and 4 hrHPV co-testing trials to examine invasive cervical cancer incidence.³⁴ Four large cohort studies were included: 1 of primary hrHPV screening (n=48,736),³⁵ 2 of co-testing (n= 351,613),^36–44 and one reporting on co-testing outcomes in 1,832 unscreened women.⁴² Trials varied in the number of reported screening rounds (1 or 2), the screening interval (3 to 5 years), consistency between screening rounds (e.g., randomization maintained, cytology only or co-testing for both intervention and control groups in the second screening round) and the protocols for evaluation of abnormal screening results. For primary hrHPV screening, follow-up varied and included cytology triage from a specimen obtained at the time of initial screening and held, hrHPV genotyping, or immediate colposcopy (Table 1). Four RCTs offered consistent evidence that primary hrHPV screening will detect higher rates of CIN3+ at an initial screening round compared with cytology, while trials of co-testing did not show initial increased CIN3+ detection at Round 1. Mortality from cervical cancer was not reported in any included studies.

Table 1.

Study Characteristics of Randomized ClinicalTrials (RCTs) and Cohort Studies of hrHPV Screening

Source	Qualitya	Study Design	Country	Ages Recruited, y	No. of Participants	Screening Strategy at Entry	No. of Screening Rounds (Screening Interval, y)	Criteria for Immediate Colposcopy	Protocol Changes Between Rounds	Follow-up Period, yb
hrHPV Primary Screening
Ronco, 201017,18 NTCC Phase II	Good	RCT	Italy	25-60	49,196	hrHPV alone	2 (3)	hrHPV+	Screening with CC in Round 2	7.0
						CC	2 (3)	LSIL+ or ASC-US+e	NA
Ogilivie, 201816,19–21,48 HPV FOCAL	Fair	RCT	Canada	25-65	19,009	hrHPV w/LBC triage	2(4)c	hrHPV+ and ASC-US+	Received co-testing at 4-year exit screen	4.0
						LBC w/HPV triage	2 (4)c	ASCUS+ and hrHPV+ or ASC-H or LSIL+	Received co-testing at 4-year exit screen
Leinonen, 201222 FINNISH	Fair	RCT	Finland	25-65	203,425	hrHPV w/CC triage	1 (5)	hrHPV+ and LSIL+	NA (single round)	5.0
						CC	1 (5)	LSIL+	NA (single round)
Canfell, 201711 Compass	Fair	RCT	Australia	25-64	4,995	hrHPV w/LBC triaged	1 (5)	HPV16/18+, other hrHPV+ with LSIL or ASC-H+ or p16/Ki-67 +	NA (single round)	5.0
						LBC	1 (2.5)	ASC-H+/HSIL+	NA (single round)	2.5
Zorzi, 201735	Fair	Cohort	Italy	25-64	48,736	hrHPV w/CC triage	2 (3)	hrHPV+ and ASC-US+	NA (single round)	6
hrHPV Co-testing with Cytology
Ronco, 201017,23,24 NTCC Phase I	Good	RCT	Italy	25-60	45,174	hrHPV w/CC	2 (3)	ASC-US+ and/or hrHPV+ among women ages 35 years or older	Screening with CC in Round 2	7.0
						CC	2 (3)	LSIL+ or ASC-US+e	NA
Rijkaart, 201225–27 POBASCAM	Good	RCT	Netherlands	29-61	44,938	hrHPV w/CC	2 (5)	HSIL+	None	9.0
						CC	2 (5)	HSIL+	Screening with co-testing in Round 2
Naucler, 200728,29 SWEDESCREEN	Fair	RCT	Sweden	32-38	12,527	hrHPV w/CC	1 (3)	ASC-US+e	Unblinding of hrHPV statusf; screening with CC in Round 2	4.1g
						CC	1 (3)	ASC-US+e	NA
Kitchener, 200930–33 ARTISTIC	Fair	RCT	United Kingdom	20-64	25,078	hrHPV w/LBC	2 (3)	HSIL+	None	4.5
						LBC	2 (3)	HSIL+	None
Katki, 201136–41 KPNC	Fair	Cohort	United States	≥30	331,818	hrHPV w/CC	2 (3)	ASC-US/hrHPV+ or LSIL+	NA	6.0
Ibanez, 201442	Fair	Cohort	Spain	40-88	1,832	hrHPV w/CC	2 (3)	hrHPV+ or ASC-US+	NA	6.0
Luyten, 201445,46 WOLPHSCREEN	Fair	Cohort	Germany	≥30	19,795	hrHPV w/CC	2 (5)	hrHPV+ and/or HSIL/ASC-H	LBC w/ p16/Ki-67 dual staining introduced as a triage test. Participants who changed health insurance provider excluded from Round 2 (n=6256).	10.0
McCaffery, 200450	Fair	Cross-sectional	United Kingdom	20-61	428	hrHPV w/CC	1 (NR)	ASC-US+, hrHPV+, or unsatisfactory smears	NA	NR

^aAssessed using criteria from the US Preventive Services Task Force⁶²

^bAll time points are maximum follow-up, with the exception of the SWEDESCREEN trial, which reported average follow-up

^cHPV FOCAL had two randomized hrHPV groups: safety group (screening every 2 years) and intervention group (screening every 4 years), only the latter is reported; results from the control arm are reported at 4 years, and include the 2 year screening round results

^dTriage could be done via LBC or dual-stained cytology

^eSome differences between trial sites

^fUnblinding of HPV status 3-years after enrollment and 4-months after the completion of Round 1

^gRange: <0.1 to 7.7 years

Abbreviations: ARTISTIC = A Randomised Trial in Screening to Improve Cytology; ASC-H = atypical squamous cells cannot exclude HSIL; ASC-US = atypical squamous cells of undetermined significance; BMD = borderline or mildly dyskaryotic smear results; CC = conventional cytology; CIN = cervical intraepithelial neoplasia;; HPV FOCAL = Human Papillomavirus For CervicAL cancer screening trial; hrHPV = high risk human papillomavirus; HSIL = high-grade squamous intraepithelial lesion;; LBC = liquid-based cytology; LSIL = low-grade squamous intraepithelial lesion; NA = Not applicable; NR = not reported; NTCC = New Technologies for Cervical Cancer Screening; POBASCAM = Population Based Screening Study Amsterdam Program

Primary hrHPV Compared to Cytology Screening

Across 4 trials with variable protocols and hrHPV test types, conducted in women aged 25 to 65 years, evidence was consistent in demonstrating that primary hrHPV screening led to a statistically significant increased detection of CIN3+ in the initial round of screening (RR range, 1.61 [95% CI,1.09 to 2.37])^16,19–21 to 7.46 [95% CI, 1.02 to 54.66]¹¹) (Table 2). Only the New Technologies for Cervical Cancer (NTCC) Phase II trial of primary hrHPV screening, in which all women with a positive hrHPV test were referred to colposcopy, had complete results from 2 rounds of screening, but the screening strategy was not maintained (at Round 2 screening all women received cytology testing).^17,18 In that study, CIN3+ detection in Round 1 was 3-times higher in the hrHPV screening group, with cumulative detection 1.8-times higher after the second round of screening. Results of a single-group cohort study of primary hrHPV screening at 3-year intervals were consistent with trial findings (eTable 2).³⁵

Table 2.

Effectiveness of hrHPV Screening for CIN3+ and Invasive Cervical Cancer Incidence, based on Randomized Clinical Trials (Key Question 1)

Source	Qualitya	Screening Round (Planned Follow-Up Period, y)	Screening Approach	CIN 3+		Invasive Cervical Cancer
				Absolute Detection (%)b	Relative Risk (95% CI)	Absolute Detection (%)b
hrHPV Primary Screening
Ronco, 201017,18 NTCC Phase II	Good	1 (3.5)	hrHPV vs. CC	IG: 97/24,661 (0.4)c CG: 33/24,535 (0.1)c	2.92 (1.97 to 4.34)d	NR
		2 (3.5)	CC vs. CC	IG: 5/23,978 (0.02)c CG: 23/24,372 (0.09)c	0.22 (0.08 to 0.58)d	NR
		Cumulative (7)	-	IG: 102/24,661 (0.4)c CG: 56/24,535 (0.2)c	1.81 (1.31 to 2.51)d	NR
Ogilivie, 201816,19–21,48 HPV FOCAL	Fair	1 (1)e	hrHPV w/LBC triage vs. LBC	IG: 67/9540 (0.7) CG: 41/9408 (0.4)	1.61 (1.09 to 2.37)	NR
		2 (4)e,f	Co-testing vs co-testing	IG: 22/9540 (0.2) CG: 52/9408 (0.6)	0.42 (0.25 to 0.69)	NR
		Cumulative (4)e,f	-	IG: 89/9,540 (0.9) CG: 93/9,408 (1.0)	0.94 (0.71 to 1.26)	NR
Leinonen, 201222 FINNISH	Fair	1 (5)	hrHPV w/CC triage vs. CC	IG: 195/66,410 (0.3) CG: 118/65,784 (0.2)	1.64 (1.30 to 2.06)d	IG: 17/66,410 (0.03) CG: 9/65,784 (0.01)
Canfell, 201711 Compass	Fair	1 (5)	hrHPV w/LBC triagef vs. LBC	IG: 30/4,000 (0.8) CG: 1/995 (0.1)	7.46 (1.02 to 54.66)	IG: 0/4,000 (0) CG: 0/995 (0)
hrHPV Co-testing with Cytology
Ronco, 201017,23,24 NTCC Phase I	Good	1 (3.5)	Co-testing vs. CC	IG: 75/22,708 (0.3)c CG: 58/22,466 (0.3)c	1.28 (0.91 to 1.80)d	NR
		2 (3.5)	CC vs. CC	IG: 13/22,093 (0.06)c CG: 19/22,330 (0.08)c	0.96 (0.34 to 1.40)d	NR
		Cumulative (7)	-	IG: 88/22,708 (0.4)c CG: 77/22,466 (0.3)c	1.13 (0.83 to 1.53)d	NR
Rijkaart, 201225–27 POBASCAM	Good	1 (4)	Co-testing vs. CC	IG: 171/19,999 (0.9) CG: 150/20,106 (0.7)	1.15 (0.92 to 1.43)	IG: 12/19,999 (0.06) CG: 6/20,109 (0.03)
		2 (5)	Co-testing vs. co-testing	IG: 88/19,579 (0.4) CG: 122/19,731 (0.6)	0.73 (0.55 to 0.96)	IG: 4/19,579 (0.02) CG: 14/19,731 (0.07)
		Cumulative (9)	-	IG: 259/19,999 (1.3) CG: 272/20,106 (1.3)	0.96 (0.81 to 1.13)	IG: 16/19,999 (0.08) CG: 20/20,106 (0.10)
Naucler, 200728,29 SWEDESCREEN	Fair	1 (3)	Co-testing vs. CC	IG: 72/6,257 (1.2) CG: 55/6,270 (0.9)	1.31 (0.92 to 1.87)	NR
		2 (NR)	CC vs. CC	IG: 16/6,257 (0.3) CG: 30/6,270 (0.5)	0.53 (0.29 to 0.98)	NR
		Cumulative (4)	-	IG: 88/6,257 (1.4) CG: 85/6,270 (1.4)	1.04 (0.77 to 1.39)d	IG: 1/6,257 (0.02) CG: 5/6,270 (0.08)
Kitchener, 200930–33 ARTISTIC	Fair	1 (2)	Co-testing vs. LBC	IG: 233/18,386 (1.3) CG: 81/6,124 (1.3)	0.96 (0.74 to 1.23)d	IG: 5/18,386 (0.03) CG: 4/6,124 (0.07)
		2 (2)	Co-testing vs. LBC	IG: 36/11,862 (0.3)g CG: 17/3,928 (0.4)g	0.76 (0.43 to 1.34)d	IG: 3/10,716 (0.03)h CG: 0/3,514 (0)h
		Cumulative (4.5)	-	IG: 269/18,386 (1.5)g CG: 98/6,124 (1.6)g	0.91 (0.73 to 1.15)d	IG: 8/18,386 (0.04)h CG: 4/6,124 (0.07h

^aAssessed using criteria from the US Preventive Services Task Force⁶²

^bThis table shows detection and relative risks for women of all ages included in the trial; for results stratified by <35 years versus ≥35 years, please see the Supplement

^cFrom author inquiry

^dCalculated (unadjusted)

^eHPV FOCAL had two randomized hrHPV groups: safety group (screening every 2 years) and intervention group (screening every 4 years), only the latter is reported; results from the control arm are reported at 4 years, and include the 2 year screening round results

^fThe 4 year results compare one round of HPV screening in the IG with two rounds of cytology screening in the CG.

^gTriage could be done via LBC or dual-stained cytology

^hPreliminary or incomplete results

Abbreviations: ARTISTIC = A Randomised Trial in Screening to Improve Cytology; CC = conventional cytology; CIN = cervical intraepithelial neoplasia;; HPV FOCAL = Human Papillomavirus For CervicAL cancer screening trial; hrHPV = high risk human papillomavirus; ; LBC = liquid-based cytology; NR = not reported; NTCC = New Technologies for Cervical Cancer Screening; POBASCAM = Population Based Screening Study Amsterdam Program

hrHPV with Cytology (Co-testing) Compared to Cytology Screening

Four co-testing trials followed enrolled women (age range 25-64 years) through 2 rounds of screening, but only 1 trial (A Randomized Trial in Screening to Improve Cytology [ARTISTIC]) maintained the randomly assigned screening protocol in the second round (Table 1).^30–33 None of the trials demonstrated significantly higher detection of CIN3+ with co-testing in the first round of screening, with the RR ranging from 0.96 (95% CI 0.74 to 1.23) to 1.31 (95% CI 0.92 to 1.87) (Table 2). By the second round of screening 3 to 5 years later, CIN3+ detection in 2 trials was significantly lower with RR’s ranging from 0.53 (95% CI, 0.29 to 0.98)^28,29 to 0.73 (95% CI, 0.55 to 0.96).^25–27 Cumulative detection of CIN3+ over 2 rounds was similar in all trials, with no RR significantly different than 1.0. Long-term follow-up was reported for 2 co-testing trials: the SWEDESCREEN trial reported up to 13 years by tracking study participants in the National Quality Registry for Cervical Cancer Prevention²⁹ and the Population-based Screening Study in Amsterdam (POBASCAM) trial reported 14 years of follow-up tracked through the nationwide network and registry of histopathology and cytopathology.²⁷ In both studies, no statistical difference in cumulative CIN3+ rates was detected between the intervention and control groups.

Two large single-group cohort studies of co-testing showed higher detection of CIN3+ in the first screening round relative to a follow-up round (eTable 2).^35,36,45,46 Long term evaluation of the U.S.-based cohort found that risk of CIN3+ in women negative on co-testing was very low 3 and 5 years after testing (0.06% and 0.1%, respectively).⁴⁴

To examine the effect of hrHPV screening on invasive cervical cancer in cervical cancer screening trials, Ronco and colleagues conducted an IPD meta-analysis of 5 trials: 4 trials of co-testing and a single trial of primary hrHPV screening (NTCC Phase II).³⁴ Participant data were pooled although these trials had distinctly different screening protocols, screening intervals, and hrHPV test types. 176,464 women with 1,214,415 person-years of follow-up were included with a total of 107 cases of invasive cervical cancer in a median follow-up period of 6.5 years. Cumulative detection of invasive cervical cancer was 46.7 per 100,000 in the hrHPV screened women, compared with 93.6 per 100,000 women in the cytology groups. With a random effects model, the overall pooled rate ratio for invasive cervical cancer in the hrHPV screened women was 0.61 (95% CI, 0.41 to 0.91). The I² test for statistical heterogeneity was not significant (0.0%, p=0.52).

Key Question 1a. Does the effectiveness of hrHPV testing to reduce cervical cancer outcomes vary by subpopulation (e.g., age, race/ethnicity, screening history, hrHPV immunization status, and socioeconomic status)?

No trials provided data on race/ethnicity, screening history, or socioeconomic status for primary hrHPV screening. Several studies reported on outcomes by age group (eTables 3 and 4) and one study reported on outcomes by age corresponding to the introduction of a population-based hrHPV immunization program.¹¹ One cohort study reported outcomes of a single round of co-testing in underscreened women.⁴²

Primary hrHPV Compared to Cytology Screening Stratified by Age

In 4 trials of primary hrHPV screening, Round 1 CIN3+ detection with hrHPV screening was consistently higher (range from 0.6%^17,18 to 2.4%^16,19–21) among women under age 35 (eTable 4) than for women older than 35 years (range from 0.2% ²² to 0.5%^16,19–21) (eTable 3). The relative risk for CIN3+ detection between screening groups, however, were similar to the overall findings in both the younger (< 30-35) and older (≥ 30-35) age groups. In the Compass trial,¹¹ participants were recruited from a population having 70% hrHPV vaccination coverage among women ages 33 and younger. Primary hrHPV screening detected higher rates of CIN3+ compared to cytology, for both the younger (25-33 years old) and older (34-64 years old) age groups. Absolute detection rates were higher for women under age 30-35 years, regardless of the screening test, in all primary hrHPV screening trials.

hrHPV with Cytology (Co-testing) Compared to Cytology Screening Stratified by Age

Three trials of co-testing reported outcomes by age group (eTables 3 and 4). CIN3+ detection was higher in women under age 30-35 years compared with older women, but no trial found a significantly higher RR for co-testing compared to cytology among women less than age 30-35 years. Among women age 35 years or older, only NTCC Phase I had a significantly higher RR for co-testing compared to cytology at Round 1 (RR 1.57 [95% CI, 1.02 to 2.43]). The effect estimates for CIN3+ detection between screening groups were generally similar across age groups, with the exception of NTCC Phase I, with a RR of 0.89 (95% CI, 0.51 to 1.57) for women age less than 35 years, and 1.57 (95% CI, 1.02 to 2.43) among women older than 35 years.

Gage and colleagues published an age-stratified analysis of 1,313,128 women in a large U.S.-based cohort who were screened for cervical cancer with co-testing from 2003 to 2013.⁴⁷ The 5-year risk of CIN3+ was highest for women aged 25 to 29 years (1.23 [95% CI, 1.09 to 1.39]), and lowest for women aged 50 to 64 years (0.25 [95% CI, 0.22 to 0.28]).

In summary, while risks of hrHPV positive results were consistently higher in women aged less than 30-35 years, in most studies differences in CIN3+ detection between screening methods were consistent across age groups.

Screening with hrHPV Co-testing in Under Screened Populations

A prospective single cohort study from Spain described the outcomes of initial co-testing in a cohort of 1,832 women older than 39 years with no documented cervical cancer screening in the previous 5 years.⁴² No comparison group was included and women over 65 years were excluded after initial co-testing was negative. Of 1,494 remaining women, 767 (51.3%) completed follow-up. Nine women were diagnosed with CIN3+, and 2 women had invasive cervical cancer (eTable 2).

Key Question 1b. For each primary screening strategy, how does the rescreening interval relate to future cancer incidence or progression?

Data were not adequate to compare outcomes of different rescreening intervals. No completed trials made direct comparisons of intervals or consistent application of initial screening strategies for more than 1 screening round. One trial (HPV Testing for Cervical Cancer Screening [HPV FOCAL])^{16,19–21,48} was designed to directly compare different rescreening intervals (2 years for cytology versus 4 years for primary hrHPV screening). ⁴⁹ CIN3+ detection was higher at initial screening in the hrHPV group compared to the cytology group(0.7% vs 0.4%; RR 1.61 [95% CI 1.09 to 2.37]) and lower at the 4-year exit round screen compared to the cytology group (0.2% vs 0.6%; RR 0.42 [95% CI 0.25 to 0.69%) (Table 2).⁴⁸ The POBASCAM trial with 5 year screening intervals exhibited CIN3+ detection and RRs for co-testing similar to those seen from co-testing trials with 3-year screening intervals.^25–27 In 13 to 14 year follow-up of the SWEDESCREEN and POBASCAM trials, CIN3+ risk remained persistently low in women who tested hrHPV negative on initial screening, suggesting 5-year intervals for hrHPV screening are no less effective than 3-year intervals over longer time frames.^27,29 Recently published analyses of the large U.S.-based co-testing cohort^43,44 evaluated the risk of CIN3+ and invasive cervical cancer at 3 and 5 years after screening and found that after a negative hrHPV test (regardless of the cytology result), risk of subsequent CIN3+ was very low at 5 years (0.114% [95% CI 0.106 to 0.122]) and only slightly lower at 3 years (0.085% [95% CI 0.079 to 0.092]). Women with a negative co-testing result followed by a second negative hrHPV test had risks of CIN3+ of 0.04% (95% CI, 0.04 to 0.05) at 3 years and 0.06% (95% CI, 0.05 to 0.07) at 5 years. For each of three age groups (30-39, 40-49, and >50 years), each consecutive negative hrHPV test was associated with progressively lower risk of CIN3+. No cases of invasive cervical cancer were detected.⁴³

Key Question 1c. Does the appropriate rescreening interval for each primary screening strategy vary by subpopulation (e.g., age, race/ethnicity, screening history, hrHPV immunization status, socioeconomic status)?

No data were available to address rescreening intervals by subpopulation.

Harms of hrHPV Screening

Key Question 2. What are the potential adverse effects of hrHPV testing, with or without cytology, as a primary screening strategy compared with currently recommended screening strategies for women in the United States?

The same 8 RCTs,^11,16–33 IPD meta-analysis,³⁴ and 3 observational cohort studies described above^35,36,46 were included for harms, along with an additional cross-sectional study of 428 women on psychological harms.⁵⁰ Studies reported screening test performance (i.e., false negative and false positive results), procedures conducted to evaluate positive screening tests (i.e., colposcopy and biopsy), and potential psychological harms (e.g., quality of life, anxiety/distress, partner discord). Overall, screening with hrHPV primary or co-testing was associated with more false positive results and higher colposcopy rates. Limited evidence suggested that positive hrHPV test results may be associated with greater psychological harm than abnormal cytology results. None of the included studies reported on harms occurring from the screening test, diagnostic testing, or treatments.

Harms of Primary hrHPV Screening

Trial differences in the protocol for follow up of positive hrHPV screening test results affected colposcopy and false positive rates. In the NTCC Phase II protocol, all hrHPV positive results were referred directly to colposcopy.^17,18 Accordingly, the false positive rate for CIN2+ was higher with hrHPV screening (7.4% vs. 3.2%) as was the colposcopy rate (7.9% vs. 2.8%) than with cytology screening in the trial (Table 3). Most women referred to colposcopy underwent the procedure (93.6% in the intervention group, 90.6% in the control group), and more women in the hrHPV screening group underwent biopsy (3.2% vs. 1.3% in the control group). The HPV FOCAL trial employed a liquid-based cytology triage strategy for hrHPV positive results.^{16,19–21,48} In Round 1 of screening 5.7% of women in the hrHPV testing group were referred to colposcopy compared to 3.1% in the cytology only control group and 94.1% of the trial participants referred to colposcopy attended.⁴⁸ Colposcopy referral rates in Round 1 of the Compass trial for hrHPV screening compared to cytology screening were3.8% vs. 2.7%.¹¹ In the FINNISH trial,²² primary hrHPV screening false positive rates (7.2%) and colposcopy referral rates (1.2%) were similar to cytology screening false positive (6.5%), and colposcopy referral rates (1.1%). In three trials where age stratified results were reported, colposcopy referrals in Round 1 of screening for women under aged 30 to 35 years ranged from 2.3% to 13.1% with hrHPV testing, compared to a range from 1.9% to 4.7 % for cytology screening (e-Table 7). Among women older than 30 to 35 years, colposcopy referrals ranged from 0.9% to 5.8% for hrHPV testing compared to 1.0% to 2.5% for cytology screening (e-Table 6).

Table 3.

Colposcopy Referrals and False Positive Rates as Harms of hrHPV Screening, based on Randomized Clinical Trials (Key Question 2)

Source	Qualitya	Screening Round (Planned Follow-Up Period, y)b	Screening Approach	Test Positivityc (%)	Colposcopy Referrals (%)	False Positive Rate % (n screened positive without CIN2+ / N total screened without CIN2+)d
hrHPV Primary Screening
Ronco, 201017,18 NTCC Phase II	Good	1 (3.5)	hrHPV vs. CC	IG (hrHPV+): 1,936/24,661 (7.9) CG (ASC-US+): 825/24,353 (3.4)	IG: 1,936/24,661 (7.9) CG: 679/25,435 (2.8)	IG: 1,799/24,428 (7.4) CG: 770/24,038 (3.2)
Ogilivie, 201816,19–21 48 HPV FOCAL	Fair	1 (1)c	hrHPV w/LBC triage vs. LBC	IG (hrHPV+): 771/9,540 (8.1)df CG(ASC-US+): 334/9,408 (3.5) df	IG: 544/9,540 (5.7)df CG: 290/9,408 (3.1) df	IG: 624/9,393 (6.6) CG: 244/9,318 (2.6)
		2 (4) c	Co-testing vs. co-testinge	IG (hrHPV+): 469/8,296 (5.7) CG (ASC-US+): 513/8,078 (6.4) df	IG: 469/9,540 (4.9) df CG: 660/9,408 (7.0) df	IG: 421/8,248 (5.1) CG: 413/7,978 (5.2)
Leinonen, 201222 FINNISH	Fair	1 (5)	hrHPV w/CC triage vs. CC	IG (hrHPV+): 4,971/62,106 (8.0)h CG (ASC-US+): 4,506/65,747 (6.9)h	IG: 796/66,410 (1.2) CG: 755/65,784 (1.1)	IG: 4,462/61,597 (7.2) CG: 4,239/65,480 (6.5)
Canfell, 201711 Compass	Fair	1 (5)	hrHPV w/LBC triage vs. LBCi	IG (hrHPV+): 277/4000 (6.9) CG (ASC-US+): 67/995 (6.7)	IG: 154/4000 (3.8) CG: 27/995 (2.7)	NR
hrHPV Co-testing with Cytology
Ronco, 201017,23,24 NTCC Phase I	Good	1 (3.5)	Co-testing vs. CC	IG (hrHPV+ or ASC-US+): 2,830/22,708 (12.5) CG (ASC-US+): 855/22,466 (3.8)	IG: 2,470/22,708 (10.9)j CG: 738/22,466 (3.3)	IG: 2,702/22,042 (12.3) CG: 771/21,972 (3.5)
Rijkaart, 201225–27 POBASCAM	Good	1 (4)	Co-testing vs. CC	IG (hrHPV+ or ASC-US+): 1,406/19,999 (7.0) CG (ASC-US+): 706/20,106 (3.5)	NR	IG: 1,149/19,742 (5.8) CG: 513/19,913 (2.6)
		2 (5)	Co-testing vs. co-testing	IG (hrHPV+ or ASC-US+): 742/19,579 (3.8) CG (hrHPV+ or ASC-US+): 774/19,731 (3.9)	NR	IG: 610/9,572 (6.4) CG: 612/9,450 (6.5)
Naucler, 200728,29 SWEDESCREEN	Fair	1 (3)	Co-testing vs. CC	IG (hrHPV+) 433/6,257 (6.9): IG (ASC-US+): 146/6,257 (6.9) CG (ASC-US+): 150/60,270 (2.4)	NR	IG: NR CG: 72/6,192 (1.2)
Kitchener, 200930–33 ARTISTIC	Fair	1 (2)	Co-testing vs. LBC	IG (hrHPV+ or ASC-US+): 4,019/18,386 (21.9%) CG (ASC-US+): 786/6,124 (12.8)	IG: 1,247/18,386 (6.8) CG: 320/6,124 (5.2)	IG: 3,566/17,933 (19.9) CG: 653/5,991 (10.9)
		2 (2)	Co-testing vs. LBC	IG (hrHPV+ or ASC-US+): 1,258/11,862 (10.6)k CG (ASC-US+): 210/3,928 (5.3)k	IG: 284/10,716 (2.7)k CG: 74/3,514 (2.1)k	IG: 1,178/10,512 (11.2)k CG: 176/3,832 (4.6)k

^aAssessed using criteria from the US Preventive Services Task Force⁶²

^bWith the exception POBASCAM and ARTISTIC, only Round 1 results were reported

^cTest positivity was defined based on trial protocol. Test findings that would lead to a clinical action, based on the study protocol, such as colposcopy or more intensive follow-up were considered test positive. Thus, in some trials, the test positivity rate in the intervention group is simply the rate of hrHPV test positivity, whereas in others it is the rate of hrHPV+ with ASC-US+.

^dThis table shows harms for women of all ages included in the trial; for results stratified by <35 years versus ≥35 years, please see the Supplement

^eCo-testing results that were positive on either hrHPV or cytology were referred for colposcopy

^fHPV FOCAL had two randomized hrHPV groups: safety group (screening every 2 years) and intervention group (screening every 4 years), only the latter is reported; results from the control arm are reported at 4 years, and include the 2 year screening round results

^gPercent of women; converted from rate per 1,000 participants

^hFrom author inquiry

ⁱTriage could be done via LBC or dual-stained cytology

^jEstimated data from figure

^kPreliminary or incomplete results

Abbreviations: ARTISTIC = A Randomised Trial in Screening to Improve Cytology; ASC-US = Atypical squamous cells of undetermined significance; CC = conventional cytology; CIN = cervical intraepithelial neoplasia;; HPV FOCAL = Human Papillomavirus For CervicAL cancer screening trial; hrHPV = high risk human papillomavirus;; LBC = liquid-based cytology; NR = not reported; NTCC = New Technologies for Cervical Cancer Screening; POBASCAM = Population Based Screening Study Amsterdam Program

False negatives for invasive cervical cancer (based on interval detection) were uncommon. The NTCC Phase II trials reported no CIN3 or invasive cervical cancer cases among screen negative women in either group in follow-up following the first round of screening (3.5 years maximum).^17,18 The larger FINNISH trial reported invasive cervical cancer among screen negative women in 0.01% (5/57,135) of the hrHPV testing intervention group and 0.003% (2/61,241) of the cytology control group participants after 1 round of screening with 5 years of follow-up.²² Data on invasive cervical cancer among screen negative women were not available for HPV FOCAL or the Compass trials.

No studies reported on the psychological effects of primary hrHPV screening.

Harms of hrHPV Co-testing

Colposcopy rates were reported in only 2 trials of co-testing (ARTISTIC and NTCC Phase I)^30–33 (Table 3). In the ARTISTIC trial, higher false positive rates were observed with co-testing relative to the cytology screening control group at Round 1 (19.9% vs. 10.9%) and Round 2 (11.2% vs. 4.6%).^30–33 The proportion of women attending colposcopy and undergoing biopsy was not reported. Only the NTCC Phase I trial reported age-stratified colposcopy and false positive rates. In this trial, hrHPV positive in women ages 35 years or older and ASC-US+ results were referred directly to colposcopy; colposcopy rates were 3 times higher for co-testing compared to cytology (10.6% vs. 3.0%).^17,23,24 Of those referred, 94% in the intervention and 91% in the control group received a colposcopy. For the SWEDESCREEN trial,^28,29 colposcopies were not reported and false positives could not be calculated. The POBASCAM^25–27 trial did not report colposcopy rates, but false positives were twice as high with co-testing (5.8% vs. 2.6%) at Round 1, and similar at Round 2 where both the intervention group and the control group received co-testing (6.4% vs. 6.5%).

The IPD meta-analysis obtained additional data from 5 trials (4 trials of co-testing and single trial of primary hrHPV screening) and reported similar overall biopsy rates for women assigned to hrHPV co-testing or primary testing compared to cytology in analysis of the POBASCAM, Swedescreen, and ARTISTIC trials which had a fixed effects pooled rate ratio for biopsy of 1.02 (95% CI 0.97, 1.07; I² 30.7%, p = 0.24). A pooled estimate calculated with the NTCC trial biopsy included had unacceptably high statistical heterogeneity (I² 99.1%, p <.0001). The rate ratio for biopsy from the NTCC trials was 2.24 (95% CI 2.09, 2.39) with hrHPV testing likely due to the direct to colposcopy triage protocol.³⁴

False negative rates were difficult to estimate. No invasive cervical cancer cases were observed in screen negative women in either screening group in two studies,^{17,23,24,30–33} and one did not report invasive cervical cancer rates among screen negative women.^28,29 In POBASCAM, 1 case of invasive cervical cancer was detected in a screened negative woman in the control group and no cases in the intervention group with 4 years follow-up on the first screening round.^25–27 In 14 years of long-term follow-up, there were not statistically significant differences in invasive cervical cancer incidence among women in the intervention who screened hrHPV negative and cytology normal at baseline and those in the control group with normal cytology at baseline.²⁷ A large U.S.-based cohort of women who received co-testing suggested hrHPV testing has few false negative cases of CIN3+ that are detected by cytology: the 5-year risk of CIN3+ was 0.12% (95% CI 0.11 to 0.12) for women testing hrHPV negative compared with 0.10% (95% CI 0.09 to 0.10) for women with negative co-testing.⁴⁴

Estimates of colposcopy rates from large observational cohort studies were similar to or lower than those observed in trials (eTable 5). Just over 6% of women were referred to colposcopy over 2 rounds of hrHPV primary screening in an Italian cohort study (n=48,751).³⁵ In a German study of hrHPV contesting (n=19,795), 3.9% of women were referred to colposcopy at the first round of screening and 1% at a second round.⁴⁶

Two included studies reported psychological effects of hrHPV co-testing.^33,50 In a substudy of the ARTISTIC trial,⁵⁰ samples of women aged 20 to 64 years were surveyed approximately 2 weeks after receiving screening results (n=2,508). Women assigned to the study intervention screening group who received hrHPV results in addition to their cytology screening results reported lower sexual satisfaction, but similar levels of distress and anxiety in the short term. A smaller cross-sectional study (n = 428) by McCaffery and colleagues⁵⁰ surveyed women 1 week after they received cervical cancer screening results and found that for women who underwent co-testing and had normal cytology, those with hrHPV positive results were more distressed and anxious than women with hrHPV negative results, and had worse feelings about their current, past and future sexual partners regardless of cytology results.

Key Question 2a. Do the adverse effects vary by subpopulation (e.g., age, race/ethnicity, and hrHPV immunization status)?

Three primary hrHPV screening trials and 1 co-testing trial reported age stratified colposcopy rates (eTables 6 and 7). In all trials, women less than age 30-35 years screened with primary hrHPV testing or co-testing had higher referral rates for colposcopy (range from 2.3% to 13.1%) than women screened with cytology (range from 1.9% to 4.7%). ^17,18,21,22 In the Compass trial of primary hrHPV screening, colposcopy referrals were higher with hrHPV screening among woman ages 25 to 33 (8.5% in the intervention group [IG] vs. 4.7% in the control group [CG]), and lower for woman ages 34 to 64 (2.6% in the IG vs. 2.2% in the CG) in both screening groups, despite expected vaccination rates in younger women of about 70%.¹¹

Key Question 2b. Do adverse effects vary by screening strategy, including by rescreening interval?

The influence of screening interval and strategy on potential harms of missed cancer cases or possible over-detection could not be directly ascertained from available evidence, due to lack of within trial interval comparisons and variability of protocols across studies. Screening intervals of included trials ranged from 2 to 5 years with the longest intervals from completed trials in FINNISH ²² and POBASCAM.^25–27 The trials with longer intervals reported some invasive cervical cancer cases among women who had tested hrHPV negative, but these trials (FINNISH and POBASCAM) also had larger samples and there were very few invasive cervical cancer cases overall, limiting inferences that can be drawn from between study comparisons. After 2 negative co-testing results, rates of invasive cervical cancer in the U.S.-based cohort were very low (0.003% [95% CI, 0.0016 to 0.0056]) and equal at 3- and 5-year screening intervals.⁴³

DISCUSSION

A summary of the evidence for this review is shown in Table 4. Four RCTs of primary hrHPV screening and 4 of co-testing (both hrHPV testing and cytology) compared the use of hrHPV screening for cervical cancer screening to cytology alone for the detection of CIN3+ and invasive cervical cancer. The evidence was consistent across trials that primary hrHPV screening increased detection of CIN3+ in the initial round of screening by as much as 2- to 3-times when compared to cytology. Evidence was mixed in co-testing trials; CIN3+ detection in Round 1 was not significantly higher for co-testing. No trials compared hrHPV primary testing to co-testing. Evidence on subgroups was limited to age and a single cohort study focused on previously underscreened women. Women under the age of 35 years had consistently higher rates of hrHPV positivity and of CIN3+, but the RR of CIN3+ detection with primary hrHPV screening or co-testing compared to cytology was similar between younger and older women.

Table 4.

Summary of Evidence by Key Question and hrHPV Screening Strategy

Screening Method	No. Studies, No. Obs (n)	Summary of Findings by Outcome	Consistency /Precision	Body of Evidence Limitations (includes reporting bias)	Study Qualitya	Applicability
KQ 1: Effectiveness of hrHPV screening or co-testing versus cytology alone for reducing cervical cancer incidence and mortality
hrHPV primary screening	4 RCTs n=282,839 1 cohort study n=48,736	In 4 RCTs reporting results over 1 to 2 rounds of screening spanning 4 to 7 years, hrHPV screening found more CIN3+ in an initial screening round. Overall CIN3+ detection ranged from 0.3% to 0.8% across studies. Invasive cancers reported in one RCT, but numbers were very small (less than 0.1%). Cohort study findings were consistent with RCTs. Mortality data were not reported.	Reasonably consistent and precise for CIN3+ detection Imprecise for invasive cervical cancer incidence.	Randomization not maintained for more than 1-2 rounds of screening; heterogeneity in screening, follow-up tests and protocol; trials underpowered to assess invasive cervical cancer incidence and mortality. Cohort study lacked a comparison group Reporting bias undetected	RCTs: 1 good, 3 fair Cohort: 1 fair	All trials in organized screening programs in European countries with nationalized health systems. Applicability lower for women in the U.S. without access to organized screening programs; higher for U.S. women with access to organized screening programs.
hrHPV co-testing with cytology	4 RCTs n= 127,717 2 cohort studies n=351,613	In 4 RCTs reporting results over 1 to 2 rounds of screening spanning 4.5 to 9 years, co-testing found similar rates of CIN3+ compared with cytology in Round 1 and cumulatively. 2/4 trials have lower CIN3+ rates in Round 2 of screening. 13-year follow-up in 1 trial did not detect a difference between groups. 2 large single group cohort studies found CIN3+ in 0.6 to 0.7% of women at initial screening. Among women who initially screened negative and were rescreened after 3 or 5 years, rates of CIN3+ were very low (0.05%). Mortality data were not reported.	Reasonably consistent and precise for CIN3+ Imprecise/ NA for invasive cervical cancer incidence.	Randomization not maintained for more than 1-2 rounds of screening; heterogeneity in screening, follow-up tests and protocol; trials underpowered to assess invasive cervical cancer incidence and mortality. Two large cohort studies had no comparison groups. Reporting bias undetected	RCTs: 2 good, 2 fair Cohorts: 2 fair	All trials were in organized screening programs in European countries with nationalized health systems. Applicability lower for women in the U.S. without access to organized screening programs, and higher for U.S. women with access to organized screening programs.
KQ1a: Subpopulation (i.e., age, unscreened women) differences in screening for reducing cervical cancer incidence and mortality
hrHPV primary screening in women aged <30-35 years	4 RCTs, n=41,914 1 cohort study n=5103	4 RCTs reported absolute detection of CIN3+; Women <35 years had higher rates of cumulative CIN3+ detection across studies, but relative detection rates between hrHPV screening and cytology were similar to overall results, including a small trial that included women vaccinated against hrHPV. Across trials CIN3+ rates ranged from 0.2% to 3.0%. The cohort study found higher rates of CIN2+ in women 25-29 years, consistent with the trials. Mortality data were not reported.	Reasonably consistent and precise for CIN3+ detection. Imprecise for invasive cervical cancer incidence.	Randomization not maintained for more than 1-2 rounds of screening; heterogeneity in screening, follow-up tests and protocol; trials underpowered to assess invasive cervical cancer incidence and mortality. Reporting bias undetected	RCTs: 1 good, 3 fair Cohort: 1 fair	All trials were in organized screening programs in European countries with nationalized health systems. Applicability lower for women in the U.S. without access to organized screening programs, and higher for U.S. women with access to organized screening programs.
hrHPV co-testing with cytology in women aged <30-35 years	3 RCTs n=23,243	3 RCTs reported on women under age 35. CIN3+ detection rates were comparable between the IG and CG for both rounds with no significant differences in cumulative CIN3+. Detection rates ranged from 0.1% to 3.3% across trials. Mortality data were not reported.	Reasonably consistent and precise for CIN3+ detection over 1-2 rounds of screening. Imprecise/ for invasive cervical cancer incidence	Randomization not maintained for more than 1-2 rounds of screening; heterogeneity in screening, follow-up tests and protocol; trials underpowered to assess invasive cervical cancer incidence and mortality. Single cohort study with no comparison group. Reporting bias undetected	2 good, 1 fair	All trials were in organized screening programs in European countries with nationalized health systems. Applicability lower for women in the U.S. without access to organized screening programs, and higher for U.S. women with access to organized screening programs.
hrHPV primary screening in women ≥30-35 years	4 RCTs n=169,714 1 cohort n=43,647	4 RCTs reported on 1-2 rounds of screening in women over age 30 to 35 years. CIN3+ outcomes were similar to the overall group results. CIN3+ detection rates ranged from 0.2% to 0.5%. The cohort study found lower rates of CIN2+ in women over age 29 years, consistent with the trials. Mortality data were not reported.	Reasonably consistent and precise for CIN3+ detection over 1-2 rounds of screening. Imprecise for invasive cervical cancer incidence.	Randomization not maintained for more than 1-2 rounds of screening; heterogeneity in screening, follow-up tests and protocol; trials underpowered to assess invasive cervical cancer incidence and mortality. Reporting bias undetected	RCTs: 1 good, 3 fair	All trials were in organized screening programs in European countries with nationalized health systems. Applicability lower for women in the U.S. without access to organized screening programs, and higher for U.S. women with access to organized screening programs.
hrHPV co-testing with cytology in women ≥30-35 years	4 RCTs n=99,073	4 RCTs reported findings from 1-2 rounds of screening. CIN3+ outcomes were similar to the overall group results, with no significant differences in cumulative CIN3+ detection in any trial. CIN3+ detection rates ranged from 0.03% to 1.4%. Mortality data were not reported.	Reasonably consistent and precise for CIN3+ detection over 1-2 rounds of screening, Imprecise/ NA for invasive cervical cancer incidence or mortality,	Randomization not maintained for more than one or two rounds of screening; heterogeneity in screening and follow-up tests and protocol; trials underpowered to assess cervical cancer incidence and mortality. Single cohort study with no comparison group. Reporting bias undetected	2 good, 2 fair	All trials were in organized screening programs in European countries with nationalized health systems. Applicability lower for women in the U.S. without access to organized screening programs, and higher for U.S. women with access to organized screening programs.
hrHPV co-testing with cytology in unscreened women	1 cohort study n=1,832	One study of underscreened women suggested one-time hrHPV co-testing would detect more CIN3 and invasive cervical cancer; of 9 CIN3+ cases, all were hrHPV+ and 6 had positive cytology.	Imprecise Consistency NA	Lack of a comparison group, substantial loss to follow-up Reporting bias undetected	1 fair	1 small single group cohort study conducted in Spain
KQ1b and KQ1c Relationship of rescreening intervals to future cancer incidence or progression
hrHPV primary screening or co-testing compared to cytology	k=0	No completed trials compared screening intervals with use of hrHPV screening. Trials comparing hrHPV screening to cytology used 2 to 5-year intervals, but given variability of screening protocols, comparison between trials was not meaningful. No evidence on subpopulations.	NA	NA	NA	NA
KQ 2: Adverse effects of hrHPV screening or co-testing versus cytology
hrHPV primary screening	4 RCTs n=282,839 1 cohort study n=48,736	In 2 trials reporting, false positive results were higher in the hrHPV-screened group (IG). All trials had higher rates of coloposcopy in the IG. False positive results in the single group cohort were approximately halved at Round 2. Screen negative invasive cervical cancer cases were not consistently reported. No studies reported on adverse events associated with screening, diagnostic screening, or treatment of CIN.	Reasonably consistent Reasonably Precise	Heterogeneity in screening FU protocols make it difficult to draw conclusions about relative harms of different hrHPV screening strategies compared to cytology alone, Limited data on harms of screening and diagnostic procedures. Not all trials reported colposcopy and biopsy rates. Reporting bias undetected	RCTs: 1 good, 3 fair Cohort: 1 fair	All trials were in organized screening programs in European countries with nationalized health systems. Applicability lower for women in the U.S. without access to organized screening programs, and higher for U.S. women with access to organized screening programs.
hrHPV co-testing with cytology	4 RCTs n= 127,717 2 cohort studies n=351,613	False positive results were consistently higher in the IG for 3 trials reporting on Round 1. Round 2 results, reported only in 1 trial were similar between groups. German cohort data from found colposcopy referral rates declined from 3.9% after Round 1 and to 1.0% at Round 2. No studies reported adverse events associated with screening, diagnostic screening, or treatment of CIN. 2 studies reported positive hrHPV test results as part of co-testing were associated with higher anxiety and distress, and lower satisfaction with current and past sexual partnerships	Reasonably consistent Reasonably Precise	Heterogeneity in screening follow-up protocols make it difficult to draw conclusions about relative harms of different hrHPV screening strategies compared to cytology alone. Limited data on harms of screening and diagnostic procedures. Not all trials reported colposcopy and biopsy rates. Reporting bias undetected	RCTs: 2 good, 2 fair Cohort: 3 fair	All trials were in organized screening programs in European countries with nationalized health systems. Applicability lower for women in the U.S. without access to organized screening programs, and higher for U.S. women with access to organized screening programs. Psychological harms assessed in women enrolled in organized screening in the UK, findings may not be fully applicable to U.S. women.
KQ2a: Subpopulations (Adverse effect differences by age)
hrHPV primary screening in women aged <30-35 years	4 RCTs, n=41,914	False positive results, reported in 1 trial, were higher in the IG. Colposcopy referral rates were higher in the IG at Round 1 screening. One RCT reported colposcopy referrals for the youngest women, ages 25 to 29, and these were the highest observed for any trial group (19.9%, 95% CI 17.9% to 22.1%). No studies reported adverse events associated with screening, diagnostic screening, or treatment of CIN by age. No trials with more than one round of screening data available reported colposcopy rates at round 2 by age. invasive cervical cancer among screen negatives and psychological harms by age were not reported.	Reasonably consistent Reasonably precise	Heterogeneity in screening follow-up protocols make it difficult to draw conclusions about relative harms of different hrHPV screening strategies compared to cytology alone. Limited data on harms of screening and diagnostic procedures. Not all trials reported colposcopy and biopsy rates.	1 good, 3 fair	All trials were in organized screening programs in European countries with nationalized health systems. Applicability lower for women in the U.S. without access to organized screening programs, and higher for U.S. women with access to organized screening programs.
hrHPV co-testing with cytology in women aged <30-35 years	1 RCT n=11,810	One RCT provided false positive rates at Round 1 with the largest differences seen among women <35. Colposcopies were consistently higher in the IG for 4 RCTs. No trials reported colposcopy rates at round 2 by age. No studies reported adverse events associated with screening, diagnostic screening, or treatment of CIN by age. False negative invasive cervical cancer results and psychological harms by age were not reported.	Reasonably consistent Reasonably precise		1 good	All trials were in organized screening programs in European countries with nationalized health systems. Applicability may be lower for women in the U.S. without access to organized screening programs, and higher for U.S. women with access to organized screening programs.
hrHPV primary screening in women ≥30-35 years	4 RCTs n=169,714	One RCT reported false positives by age with higher rates in the IG. 4 RCTs reported colposcopy referrals at round 1. Rates were higher in the IG but lower overall than in women <30-35 years. No studies reported on harms associated with screening, diagnostic testing, or treatment of CIN by age. No trials reported colposcopy rates at round 2 by age. False negative invasive cervical cancer results and psychological harms by age were not reported.	Reasonably consistent Reasonably precise		1 good, 3 fair	All trials were in organized screening programs in European countries with nationalized health systems. Applicability lower for women in the U.S. without access to organized screening programs, and higher for U.S. women with access to organized screening programs.
hrHPV co-testing with cytology in women ≥30-35 years	1 RCT n=33,364	1 RCT reported false positives and colposcopy referrals & found higher rates for both in the IG, but somewhat lower than those in women <30-35 years. No trials reported colposcopy rates at round 2 by age. False negative results and psychological harms by age were not reported.	Reasonably consistent Reasonably precise		1 good	All trials were in organized screening programs in European countries with nationalized health systems. Applicability lower for women in the U.S. without access to organized screening programs, and higher for U.S. women with access to organized screening programs.
KQ2b and KQ2c Relationship of rescreening intervals to future cancer incidence or progression
hrHPV primary screening or co-testing compared to cytology	k=0	No completed trials compared screening intervals with use of hrHPV screening. Trials comparing hrHPV screening to cytology used 2 to 5 year intervals, but given variability of screening protocols comparison between trials was not meaningful. No evidence on subpopulations.	NA	NA	NA	NA

Abbreviations: CIN, cervical intraepithelial neoplasia; CG, control group; EPC, Evidence-based Practice Center; FU, follow-up; hrHPV, high risk human papillomavirus; IG, intervention group; KQ, key question; NA, not applicable; NR, not reported; Obs, observations; RCT, randomized clinical trial; US, United States; UK, United Kingdom.

^aAssessed using criteria from the US Preventive Services Task Force⁶²

False positive rates were higher in the intervention group for both primary hrHPV screening and co-testing in the first screening round. Colposcopy referrals were consistently reported, but biopsy rates were not, limiting estimation of the downstream harms of screening. In 3 primary hrHPV screening trials and all co-testing trials, colposcopy referrals were higher in the intervention group, indicating a greater relative burden with hrHPV screening and potential differences in downstream consequences of treatment compared to screening cytology. Harms of treatment of the cervix to remove precancerous cells were not reported in any of the included studies, but include pain and bleeding, which on rare occasion requires vaginal packing or transfusion.^51,52 Harms related to subsequent pregnancy outcomes, particularly risk of second trimester pregnancy loss and preterm birth, may occur after cold knife conization or loop electrosurgical excision procedure (LEEP) deeper than 10 millimeters.^{53, 54} Limited evidence suggested that hrHPV test positivity may be associated with greater short-term psychological harm than abnormal cytology results.^30–33

Cervical cancer incidence and mortality have substantially decreased since the introduction of screening programs over half a century ago; the lowest rates are found in countries with organized screening programs. All of the RCTs included in this review were conducted in countries with robust, organized screening programs. Organized screening programs are well suited for comparative trials of screening strategies; however, the generalizability of findings from this review to women in the United States is limited by the lack of organized screening programs for the majority of U.S.-based women. Most cervical cancer screening in the United States is opportunistic, without population-based registries or regular invitations to screening. Over 50% of women diagnosed with cervical cancer in the United States have not been screened in the prior 3 to 5 years.⁵⁵ The highest proportions of unscreened women are those without insurance (23.1%) or no regular clinician (25.5%).⁵⁶

Cervical cancer predominantly affects underscreened women in the United States, thus a substantial effect on cervical cancer incidence and mortality requires the identification of effective outreach strategies. Limited evidence from a single cohort study of poorly screened women in Spain suggests that the increased sensitivity of hrHPV screening may be particularly important for early detection among under screened women.⁴² Several systematic reviews summarize evidence that hrHPV screening via self-collection may be a sufficiently accurate and acceptable strategy for reaching under- and unscreened populations.^57,58,59 Further research is needed to examine the effect of self-collection screening strategies on overall screening rates, adherence to follow-up, and health outcomes for women with limited access to health care or low rates of participation in screening programs.^60,61

LIMITATIONS

This review was limited by the quality and heterogeneity of the included studies. First, the quality of many of the included studies was rated as fair due to problems with attrition, protocol changes, and lack of blinding of outcome assessment. Second, the overall body of evidence was limited by trials having no more than 2 and often only 1 randomized round of screening available for comparisons. Only 1 trial (ARTISTIC) maintained the same strategy over 2 rounds of screening.^30–33 Third, outcome reporting on colposcopy and biopsy rates was inconsistent, and none of the trials reported on adverse events associated with the screening tests or diagnostic and treatment procedures resulting from screening. Finally, the trial evidence was supplemented with results of large cohort studies of primary hrHPV screening or co-testing over 2 screening rounds, however, none of the cohort studies had a comparison group screened with cytology only.

CONCLUSIONS

Primary hrHPV screening detected higher rates of CIN3+ at first round screening compared with cytology. Co-testing trials did not show initial increased CIN3+ detection. Both hrHPV screening strategies had higher false positive and colposcopy rates than cytology, which could lead to more treatments with potential harms.