Skip to main content
NCBI home page
Karger Author's Choice logoLink to Karger Author's Choice
. 2025 May 31;48(11):704–715. doi: 10.1159/000546717

Follow-Up Time of Anal Cancer Screening among Women Living with HIV at High Risk of Developing Anal Cancer

Steven P Masiano a,b,c,✉, Tiffany L Green c,d, Bassam Dahman c, April D Kimmel c,e,✉
PMCID: PMC12215150  NIHMSID: NIHMS2088353  PMID: 40451173

Abstract

Introduction

Screening for anal cancer can help in its secondary prevention. We examined follow-up time for anal cancer screening among high-risk women living with HIV (WLHIV) and whether it varies with the number of risk factors for developing anal cancer.

Methods

A retrospective cohort study involving high-risk WLHIV under 65 enrolled in Medicaid for at least 2 years across 16 US states plus D.C. from 2009 to 2012. High risk was defined by a history of abnormal cervical test results or genital warts. Initial anal cancer screening was the first screening after a high-risk diagnosis, with results classified as normal or abnormal. Follow-up was until the next screening. Follow-up time was analyzed using the Kaplan-Meier estimator and the Cox Proportional Hazards model.

Results

Our cohort included 4,340 high-risk WLHIV, mean (±SD) age 41.8 (±10.2) years. About 18% (763/4,340) had both risk factors, while 9% (374/4,340) had abnormal results on their initial anal cancer screening. The median time, or the time at which 50% of the cohort received follow-up screening, was 17.53 (95% CI = 16.13, 18.30) months overall. Follow-up screening was more common in women with both risk factors for developing anal cancer compared to those with one risk factor (median time: 10.13 [95% CI = 8.90, 11.47] vs. 19.56 [95% CI = 18.36, 21.40] months; adjusted hazard ratio [aHR] = 1.53 [95% CI = 1.38, 1.68]). The follow-up was also more common in women with abnormal results on the initial screening compared to those with a normal result (median time: 7.00 [95% CI = 5.40, 9.23] vs. 18.91 [95% CI = 17.92, 20.12] months; aHR = 2.00 [95% CI = 1.76, 2.28]).

Conclusion

Follow-up time for anal cancer screening in high-risk WLHIV was about 1.5 years but varied according to the risk of developing anal cancer. Future research should examine the guideline-concordance of follow-up screening time given the recently issued guidelines for anal cancer screening.

Keywords: Women living with HIV, Anal cancer, Follow-up screening, Medicaid, Hazard ratio

Plain Language Summary

Women living with HIV (WLHIV) who have had abnormal cervical test results or genital warts are at a higher risk of developing anal cancer. Since screening for anal cancer can help catch the disease early, we looked into how long it takes for high-risk WLHIV to receive follow-up screening after their initial screening. We focused on high-risk WLHIV under 65 years old who had been on Medicaid for at least 2 years across 16 US states and D.C. from 2009 to 2012. Our study included data from 4,340 high-risk WLHIV. Among these women, two out of five had two risk factors for developing anal cancer, while one in 10 had an abnormal result on the initial screening. The average age of the women was 42 years. We found that half of the women received follow-up screening within 18 months after the initial screening. However, this follow-up time varied by group. Women with two risk factors received follow-up screening sooner than those with one risk factor, who took much longer. Similarly, women who had an abnormal result on the initial screening also received follow-up screening sooner than those with a normal result. This shows that high-risk WLHIV do receive follow-up screenings, but the timing depends on their risk for anal cancer. In the future, it would be helpful to see if the follow-up times for these high-risk WLHIV align with the latest guidelines for anal cancer screening.

Introduction

Over the past two to three decades, anal cancer has seen the most significant rise in incidence among all non-AIDS-defining cancers [1–4]. Among women living with HIV (WLHIV), the incidence of anal cancer has increased by 40% during this time frame [5–8], reaching rates of 22–30 cases per 100,000 person-years – at least twelve times higher than in women without HIV [1, 9, 10]. This alarming disparity highlights the need for a better understanding of anal cancer screening practices within this demographic.

Anal cancer screening facilitates the early detection of abnormal anal cells, enabling effective secondary prevention measures [11–13]. Studies indicate that anal intraepithelial neoplasia (AIN), which consists of these abnormal cells, is found in 12–42% of WLHIV [14–19]. Importantly, untreated AIN can progress rapidly, advancing from low- to high-grade AIN within 2 years and potentially developing into anal cancer in less than a year [12]. However, with appropriate screening and treatment, the progression of AIN is significantly slowed, reducing the likelihood of progression to anal cancer by 57% among those diagnosed with high-grade AIN, according to a recent randomized control trial [13]. Additionally, timely intervention is associated with improved 5-year survival rates for localized, regional, and metastatic anal cancers [20].

Among people living with HIV (PLHIV), women with a history of abnormal cervical tests or genital warts, as well as men who have sex with men (MSM), are recognized as groups at an elevated risk for developing anal cancer and are, therefore, the most likely to benefit from anal cancer screening [21–23]. However, much of the existing literature regarding the frequency of anal cancer screening in PLHIV has primarily focused on MSM [24–30], with WLHIV, regardless of the risk for anal cancer, often overlooked. In the few studies that have included WLHIV, the sample sizes have typically been small, the geographic scope small [17, 19, 26, 27, 31], or the findings have not been reported by specific risk factors for acquiring anal cancer [32, 33], which limits the generalizability of the results. Additionally, while there is some evidence supporting initial anal cancer screening for WLHIV [14–19, 31], there is a notable absence of research on the frequency of follow-up screenings in other PLHIV, especially among WLHIV with abnormal cervical tests or genital warts – two populations that we collectively classify as high-risk and have been identified as such in the literature [21–23].

The present study investigates the frequency (time) of follow-up anal cancer screening among high-risk WLHIV. Additionally, we explore whether the timing of follow-up screenings varies by the number of risk factors associated with anal cancer. We hypothesize that WLHIV presenting with both risk factors for anal cancer have a greater need for healthcare services and, therefore, a shorter follow-up time as they have a higher risk of developing anal cancer than those with one risk factor [34]. To address these research questions, as well as overcome some limitations identified in previous studies, we created a large 4-year retrospective cohort of high-risk WLHIV continuously enrolled in Medicaid – the largest payer of HIV care in the USA [35].

Methods

Study Design and Data Sources

This retrospective cohort study examined high-risk WLHIV continuously enrolled in Medicaid for a minimum of 24 months across the US South (16 states plus the District of Columbia) from 2009 to 2012. We utilized Medicaid Analytic eXtract (MAX) files to identify high-risk WLHIV and analyze the frequency of anal cancer screening. MAX data include person-level information such as Medicaid eligibility, demographic details (age, sex, race, and ethnicity), and healthcare service utilization [36]. These data are particularly well-suited for our study, as the US South has the highest number of PLHIV, and Medicaid is the largest single-payer for HIV care in the nation [35]. Although these data are from a decade ago, our findings remain pertinent, given that practice patterns seldom change rapidly [37, 38]. Additionally, a recent publication using data from a similar timeframe highlighted the value of these data in anal cancer research [1].

We supplemented the MAX data with contemporary county-level income information from the Area Health Resources File, county-level HIV prevalence from AIDSVu, and state-level Medicaid managed care penetration data from the Kaiser Family Foundation (online suppl. Table A; for all online suppl. material, see https://doi.org/10.1159/000546717). While the supplementary data are not at the individual level and may be less precise, they still provide valuable insights, as an individual’s health is often influenced by their residential environment [39]. This study, which involved fully de-identified person-level data, received expedited approval from the Institutional Review Board of Virginia Commonwealth University (IRB#: HM20008091). The data were utilized in accordance with a data use agreement with CMS (DUA#: RSCH-2017-51616). Written informed consent was not required since the person-level data were fully de-identified.

Sample

The study sample comprised WLHIV at high risk of anal cancer, aged 19–64 years, and continuously enrolled in Medicaid in a single state for ≥24 months during the study period (Fig. 1). The sample was derived from a larger pool of Medicaid enrollees confirmed to be living with HIV [40]. From that sample, we excluded males, enrollees with unspecified sex, individuals outside the 19–64 age range, and those also eligible for Medicare. Additionally, we removed WLHIV who were not considered at high risk for anal cancer, specifically those without a history of abnormal cervical tests or genital warts (online suppl. Table B). To minimize the impact of churning, we also excluded women who were not continuously enrolled in Medicaid for at least 24 months [41, 42]. Finally, we excluded enrollees without any record of anal cancer screening after a high-risk diagnosis (online suppl. Table C).

Fig. 1.

Fig. 1.

Open in a new tab

Algorithm for identifying women living with HIV at high risk of developing anal cancer from Medicaid Analytic eXtract (MAX) files. The figure shows exclusions used to create a sample high-risk group of women living with HIV (WLHIV) for anal cancer, defined as those with a history of abnormal cervical tests or genital warts. The sample is drawn from Medicaid beneficiaries confirmed to have HIV.

Initial Screening, Follow-Up Screening, and Follow-Up Time

We defined initial anal cancer screening as the first screening conducted after a high-risk diagnosis within our data, with any subsequent screenings classified as follow-up screenings. The follow-up time was measured in days from the date of the initial screening to the date of the second screening (the first follow-up). For each enrollee, the follow-up time could span contiguous years. To classify the initial screening result as either normal or abnormal, we used ICD-9 codes indicating an abnormal result, irrespective of the method for the anal cancer screening (online suppl. Table D) [43].

Statistical Analysis

All statistical analyses adhered to the STROBE guidelines for observational studies. We summarized continuous variables as means with standard deviations and categorical variables as counts with proportions, applying t tests and chi-square tests for group comparisons. In unadjusted analyses, follow-up time was estimated overall and for subgroups number of anal cancer risk factors (one or two) and results from the initial screening (normal/abnormal) using the Kaplan-Meier method, with results reported as median time. The median time, which represents the point at which 50% of the at-risk subpopulation received follow-up screening, was utilized due to the right-skewed distribution of overall follow-up time (χ2 = 1,777 (2), p < 0.001). The log-rank test assessed differences in median follow-up time between groups [44]. We also report proportions screened at 6 and 12 months to facilitate comparisons with the literature.

Finally, we evaluated the risk of follow-up screening using the Cox Proportional Hazard model, adjusting for state-fixed effects and potential confounders detailed in online supplementary A. We checked the proportionality of the hazard assumption using three approaches. First, we checked whether the covariates had a slope of zero individually or collectively in a global test, and these tests showed the assumption was satisfied (global test [χ2 = 47 (37), p = 0.12]). The assumption was also confirmed in the second and third tests, examining log (survival) graphs against log (analysis time) for each variable and plotting Schoenfeld residuals against analysis time for each variable [94, 95] (online suppl. Fig S1, S2). Finally, we assessed the goodness-of-fit using Cox-Snell residuals, plotting cumulative hazards against the residuals to compare with the standard exponential distribution. A good fit implies that the cumulative hazard function, conditioned on covariates, follows an exponential distribution with a hazard rate of 1 [95]. We transformed continuous variables like age into categorical variables to enhance model fitness, and in the end, the model was a good fit for the data (online suppl. Fig. S3). We found no issues with multicollinearity (mean VIF = 6.10) [45]. All statistical tests were conducted as two-sided. Because having an abnormal result on the initial result was not independent of the number of risk factors (χ2 (1) = 103, p < 0.001), we further disaggregated the analysis post hoc to create groups of women with varying levels of risk for developing anal cancer and used the Nelson-Aelen cumulative hazard to assess the frequency or cumulative risk of experiencing follow-up anal cancer screening in each group. As we had multiple hypotheses, we adjusted for multiple testing using Bonferroni correction, with a p value of ≤0.025 considered statistically significant instead of the conventional ≤0.05. In sensitivity analysis, we expanded the list of diagnostic codes to capture individuals with potential histories of abnormal cervical tests or genital warts to address possible coding discrepancies or practice differences [46].

Results

Descriptive Statistics

Our sample comprised 4,340 high-risk WLHIV, with an average age was 42 years. Among these women, approximately 18% (763/4,340) presented with both risk factors for developing anal cancer (Table 1). Among the 9% (374/4,340) who had an abnormal result on their initial screening, the proportion with both risk factors for anal cancer was more than double the proportion with only one factor (18% vs. 7%). In terms of race, the proportion of women with both risk factors for developing was higher in non-Hispanic Whites and Hispanics but lower in Blacks. Additionally, women with both risk factors were higher in the proportion that qualified for Medicaid through the disability path and maintained continuous program enrollment for 4 years. Finally, over half (54%) had follow-up screening during the study’s 4-year analytic time horizon.

Table 1.

Characteristics of a retrospective cohort of high-risk women living with HIV continuously enrolled in Medicaid for at least 2 years (n = 4,340)

Variable Total (n = 4,340) Single risk factor1 (n = 3,577) Both risk factors1 (n = 763) p value
Received any follow-up anal cancer screening
 No 1,998 (46%) 1,780 (50%) 218 (29%) <0.001
 Yes 2,342 (54%) 1,797 (50%) 545 (71%)
Result of the initial anal cancer screening
 Normal 3,966 (91%) 3,340 (93%) 626 (82%) <0.001
 Abnormal 374 (9%) 237 (7%) 137 (18%)
Age, years
 19 to <35 1,162 (27%) 928 (26%) 234 (31%) 0.001
 35 to <45 1,378 (32%) 1,142 (32%) 236 (31%)
 45 to <55 1,388 (32%) 1,142 (32%) 246 (32%)
 55 to <65 411 (9%) 364 (10%) 47 (6%)
Race/ethnicity
 Non-Hispanic White 523 (12%) 424 (12%) 99 (13%) 0.009
 Non-Hispanic Black 2,927 (67%) 2,434 (68%) 493 (65%)
 Hispanic 205 (5%) 152 (4%) 53 (7%)
 Other race/ethnicity 685 (16%) 567 (16%) 118 (15%)
Medicaid qualification
 Income 1,127 (26%) 961 (27%) 166 (22%) 0.003
 Disability 3,213 (74%) 2,616 (73%) 597 (78%)
Enrollment length
 Continuously enrolled for 2 years only 877 (20%) 744 (21%) 133 (17%) 0.011
 Continuously enrolled for 3 years only 682 (16%) 577 (16%) 105 (14%)
 Continuously enrolled all 4 years 2,781 (64%) 2,256 (63%) 525 (69%)
Open in a new tab

Values are n (%).

1The two risk factors for anal cancer were (1) a history of abnormal cervical test results and (2) a history of genital warts.

Time to Follow-Up Screening

The median follow-up time of anal cancer screening exceeded 1 year overall but varied based on the risk factors for anal cancer and initial results, ranging from less than 6 months to nearly 2 years. The median follow-up time was 17.53 (95% CI = 16.13, 18.30) months. At 6 and 12 months, the proportions with any follow-up screening were 27% (95% CI = 25%, 28%) and 41% (95% CI = 39%, 42%), respectively. In subgroup analysis, the median follow-up time was 10.13 (95% CI = 8.90, 11.47) months in women with both risk factors for anal cancer compared to those with only one risk factor at 19.56 (95% CI = 18.36, 21.40) months (χ2 (1) = 105, p < 0.001) (Fig. 2). In terms of initial screening results, the median follow-up time for women with an abnormal result was 7.00 (95% CI = 5.40, 9.23) months, significantly shorter in women with a normal result, who had a median of 18.90 (95% CI = 17.97, 20.06) (χ2 (1) = 163, p < 0.001) months. The shortest median follow-up time was observed in WLHIV with both risk factors for anal cancer and also had an abnormal screening result on the initial screening, at 5.37 (95% CI = 4.40, 6.87) months. In contrast, the longest follow-up time was recorded for those with a single risk factor for anal cancer and a normal initial result, lasting 20.80 (95% CI = 19.43, 23.00) months.

Fig. 2.

Fig. 2.

Open in a new tab

Kaplan-Meier estimates of the time to follow up anal cancer screening among women living with HIV by the number of risk factors for developing anal cancer. The figure shows that the follow-up time for anal cancer screening is shorter in women with both risk factors compared to those with only one risk factor. This difference is statistically significant as there is no overlap between the confidence intervals for the estimated median follow-up times of the two groups: 10.13 (95% CI = 8.90, 11.47) months for women with both risk factors vs. 19.57 (95% CI = 18.37, 21.40) months for those with a single risk factor.

Occurrence “Risk” of Follow-Up Screening

In adjusted analyses, follow-up screening occurred more frequently in women at greater risk of developing anal cancer (Table 2). The occurrence of follow-up screening was higher in women with both risk factors for developing anal cancer compared with one risk factor, with an adjusted hazard ratio (aHR) of 1.53 (95% CI = 1.38, 1.68). Similarly, women with abnormal results on their initial screening had follow-up screening more frequently than those with normal results (aHR = 2.00 [95% CI = 1.76, 2.28]). In addition, follow-up screening also occurred more frequently in older WLHIV, those who qualified for Medicaid via the disability path. However, follow-up screening occurred less frequently in counties with more specialists.

Table 2.

Occurrence of follow-up anal cancer screening in high-risk women with HIV

Main analysis (n = 4,340) Sensitivity analysis (n = 5,129)
HR (95% CI) p value HR (95% CI) p value
Individual-level variables
 Number of risk factors for anal cancer (ref: single factor)1
  Both factors 1.53 (1.38, 1.69) <0.001 1.52 (1.38, 1.67) <0.001
 Result of the initial anal cancer screening (ref: normal)
  Abnormal result 2.00 (1.76, 2.27) <0.001 1.96 (1.73, 2.21) <0.001
 Age (ref: 19 to <35 years)
  35 to <45 1.20 (1.06, 1.34) <0.01 1.26 (1.13, 1.41) <0.001
  45 to <55 1.19 (1.05, 1.34) <0.01 1.27 (1.13, 1.42) <0.001
  55 to <65 1.31 (1.12, 1.52) <0.001 1.34 (1.16, 1.55) <0.001
 Race/ethnicity (ref: non-Hispanic White)
  Non-Hispanic Black 0.98 (0.85, 1.12) 0.72 0.99 (0.87, 1.12) 0.84
  Hispanic 1.16 (0.94, 1.44) 0.17 1.11 (0.91, 1.35) 0.32
  Other race/ethnicity 1.02 (0.84, 1.24) 0.86 1.05 (0.88, 1.27) 0.57
 Medicaid qualification path (ref: income)
  Disability 1.16 (1.04, 1.31) <0.01 1.14 (1.03, 1.27) 0.01
 Medicaid continuous enrollment (ref: 2 years)
  3 years 0.98 (0.85, 1.13) 0.79 0.95 (0.84, 1.08) 0.48
  4 years 0.93 (0.83, 1.04) 0.19 0.90 (0.82, 0.99) 0.03
County-level variables2
 HIV prevalence per 100,000 adults (ref: 0–54)
  55–138 1.51 (0.71, 3.20) 0.28 1.48 (0.73, 3.02) 0.28
  139–2,426 1.34 (0.64, 2.79) 0.44 1.49 (0.74, 2.99) 0.26
 Physician 10,000 population (ref: 0–3.7)
  3.8–6.3 1.16 (0.91, 1.48) 0.24 1.19 (0.94, 1.50) 0.14
  6.4–47.6 1.20 (0.92, 1.57) 0.18 1.21 (0.94, 1.56) 0.14
 Specialists per 10,000 population (ref: 0–0.92)
  0.93–3.4 0.76 (0.55, 1.05) 0.10 0.80 (0.59, 1.08) 0.14
  3.5–147.8 0.69 (0.49, 0.98) 0.04 0.70 (0.50, 0.98) 0.04
 Percent poor (ref: 0.9%–13.5%)
  13.6%–18.9% 0.91 (0.75, 1.11) 0.35 0.89 (0.74, 1.06) 0.20
  19%–63.2% 0.86 (0.69, 1.08) 0.20 0.83 (0.68, 1.02) 0.08
 Less than high school (ref: 1%–11.4%)
  11.5%–18% 0.98 (0.84, 1.14) 0.81 1.04 (0.90, 1.19) 0.61
  18.1%–55% 1.11 (0.91, 1.36) 0.29 1.17 (0.97, 1.40) 0.10
State-level variables2,3
 Medicaid managed care enrollment (ref: ≤60%)
  61%–80% 0.71 (0.34, 1.48) 0.36 0.87 (0.42, 1.82) 0.72
  >80% 0.84 (0.41, 1.73) 0.64 1.05 (0.51, 2.15) 0.89
Open in a new tab

HR, hazard ratio; 95 CI, 95% confidence interval.

1Risk factors for developing anal cancer are (1) a history of abnormal cervical test results and (2) a history of genital warts.

2County and state control variables are tertiles.

3State-fixed effects were included in the model but are not shown in the table for brevity.

In posthoc analysis further disaggregating the risk of developing anal cancer, follow-up screening was highest in women with both risk factors for anal cancer who also had abnormal results on the initial screen (Fig. 3). For example, within 12 months, the “accumulated” follow-up screening in women with both risk factors for anal cancer and abnormal results on the initial screen estimated using the Nelson-Aelen cumulative hazard was 1.33 (95% CI = 1.07, 1.65) compared to 0.44 (95% CI = 0.42, 0.47) in women with a single risk factor for anal cancer and a normal result on the initial screen. This difference only grew with the passage of time.

Fig. 3.

Fig. 3.

Open in a new tab

Cumulative hazards of follow-up anal cancer screening among women living with HIV disaggregated by risk of developing anal cancer. The figure shows that follow-up anal cancer screening was most common among women with both risk factors and an abnormal initial result, while it was the least common among those with only one risk factor and a normal result.

Sensitivity Analysis

Including more ICD-9 and CPT codes expanded our sample from 4,340 to 5,129 (+18%), but the associations among key variables remained largely unchanged (Table 2). Among the control variables, continuous enrollment for 4 years was significantly associated with a lower occurrence of follow-up screening than those enrolled for 2 years. However, there was considerable overlap in the confidence intervals of the hazard ratios from the sensitivity analysis (aHR = 0.90 [95% CI = 0.82, 0.99]) and main analysis (aHR = 0.93 [95% CI = 0.83, 1.04]).

Discussion

We examined the follow-up time of anal cancer screening in high-risk WLHIV and whether it differed based on having one or two risk factors for developing anal cancer. The risk factors included a history of abnormal cervical test results and genital warts. To our knowledge, this is the first study to report the follow-up time of anal cancer screening by the number of risk factors for developing anal cancer in a relatively large sample of high-risk WLHIV. Our findings suggest that high-risk WLHIV do receive follow-up screenings for anal cancer, with a median follow-up time of 18 months. However, this varies by risk level; those with two risk factors and an abnormal initial result had the shortest follow-up at under 6 months, while those with one risk factor and a normal result had the longest follow-ups at around 24 months. In sensitivity analyses, these findings remained robust.

Overall, the follow-up time for anal cancer screening varied significantly, with most women waiting over a year to be screened, particularly those who presented with one risk factor and had a normal result on the initial screening. This finding is not unexpected, as at the time of the study, there were still unresolved questions regarding who is at risk for anal cancer, the advantages of screening, and the appropriate steps to take following a positive yet inconclusive result [47]. These unresolved issues, coupled with the absence of universally adopted guidelines for anal cancer screening at that time, resulted in practice variations among different organizations [43, 48], many clinicians not discussing anal cancer screening with their patients [49], nearly two-thirds of individuals at risk for anal cancer not being aware that screening was recommended [50], and a sizable proportion of those at risk refusing to undergo anal cancer screening [50–52]. Some of these challenges should now be addressed, given the guidelines for anal cancer screening have now been developed [53]. These guidelines were developed after a randomized controlled trial demonstrated that treating high-grade squamous lesions (HSIL) in PLHIV compared to monitoring alone significantly lowers the risk of developing anal cancer [13].

A second possible explanation for the longer follow-up time for anal cancer screening is that specialists may lack the time to offer these services. Our findings indicate that high-risk WLHIV residing in counties with more specialists are significantly less likely to receive follow-up screening. In contrast, those in areas with more primary care physicians tend to have slightly higher follow-up screening frequency. This suggests that WLHIV relying on specialists vs. primary care physicians may face delays in receiving follow-up anal cancer screening. A third possible explanation is that the utilization of high-resolution anoscopy – the gold standard for anal cancer screening and recommended for follow-up screening [43, 53–55] – is hindered by shortages of colposcopies and well-trained personnel, as well as a long learning curve to master the technique [21, 56, 57]. Improving collaboration between primary care and specialists and training more providers could help address these challenges.

The pattern of the time to follow-up screening among those with abnormal and normal results on the initial screening is consistent with the literature, although the overall follow-up time in the present study is not always consistent with those studies. Earlier studies have shown that women with abnormal results tend to have higher follow-up screening frequencies compared to those with normal results [17, 19, 32]. Our overall follow-up time of 18 months is similar to findings from a study in California (17 months) [32], but longer than was reported in New York (12 months) [19]. Studies of WLHIV in Boston, Connecticut, and Massachusetts reported a follow-up time of 6 months for those with normal results on the initial screen [17, 31] – much shorter than the 19 months reported in this study. However, those studies did not restrict their samples to high-risk WLHIV, had smaller sample sizes (<100 in many cases), or were limited in geographic scope.

Our study contributes to a broader literature on the unmet healthcare needs among PLHIV, revealing that under 50% of high-risk WLHIV received follow-up screening within a year. This is consistent with other studies showing similarly low proportions of PLHIV/WLHIV receiving depression care (<50%) [58], cervical cancer screening (<40%) [59], opioid therapy (<40%) [60], medical care for HIV symptoms (<30%) [61], regular HIV care (<50%) [62].

To further contribute to this literature, future research should investigate racial/ethnic disparities in the follow-up time of anal cancer screening among WLHIV. Evidence indicates that racial/ethnic minorities are less likely to receive HIV-related preventive care [63–65], be treated for anal cancer [66], and tend to present with more advanced disease [67, 68], compared to non-Hispanic Whites. Among MSM with HIV, non-Hispanic Blacks are screened less frequently for anal cancer [30, 52, 69], but it remains unclear if this disparity exists for WLHIV. We did not investigate these disparities because of inadequate sample sizes for non-Hispanic White and Hispanic WLHIV. Future research should also examine whether the follow-up time of anal cancer screening varies by health service delivery or payment models as many states have transitioned from Medicaid fee-for-service to managed care [70]. In addition, future inquiries should also investigate the implementation and impact of the recently issued guidelines on anal cancer screening rates in general and follow-up screening specifically.

This study has several limitations. First, we could not include WLHIV who have a history of receptive anal intercourse – another group of WLHIV at high risk of developing anal cancer [23]. We could not identify specific diagnoses of receptive anal intercourse in the MAX data. Nevertheless, we likely captured some of these women among those who have histories of genital warts as individuals engaging in high-risk sexual behaviors like receptive anal intercourse are more likely to acquire sexually transmitted infections, including genital warts [71]. Second, our findings may not be generalizable as our sample was not nationally representative. The reported follow-up screening times may not be observed in the country’s other regions, among those privately insured, or those utilizing Ryan White HIV clinics.

Conclusion

The rising incidence of anal cancer among WLHIV puts a spotlight on anal cancer screening, which is essential for effective secondary prevention in this population. While WLHIV at greater risk of developing anal cancer receive follow-up screening, the follow-up time is much longer for the majority of WLHIV and consistent with reports of unmet healthcare needs among PLHIV. With established guidelines for anal cancer screening now in place, future research should focus on investigating the frequency of anal cancer screening – both initial and follow-up – and whether it is guideline-concordant across different groups of PLHIV, including high-risk WLHIV.

Acknowledgments

The authors thank the following people at Virginia Commonwealth University: doctoral students (2014–2018 class), Yangyang Den (Data Scientist), Rose Bono (Project Coordinator), and Dr. Daniel Nixon, DO, for their contribution to this work. The authors also thank the Staff at the University of Florida and the Cleveland Clinic, where this work was presented. The authors are also grateful to the anonymous reviewers of this article.

Statement of Ethics

This human study was approved by Virginia Commonwealth University’s Institutional Review Board (IRB #: HM20008091). In accordance with local/national guidelines, written informed consent from participants was not required.

Conflict of Interest Statement

The authors have no conflicts of interest to declare.

Funding Sources

This research was supported by the National Institute on Minority Health and Health Disparities of the National Institutes of Health (Award No. R01MD011277) and internal funds at Virginia Commonwealth University (VCU) for SPM’s doctoral research. The funder had no role in the design, data collection, data analysis, and reporting of this study.

Author Contributions

Steven P. Masiano: conceptualization, methodology, formal analysis, visualization, writing – original draft, and validation. Tiffany L. Green and Bassam Dahman: methodology, writing – review and editing, and validation. April D. Kimmel: conceptualization, methodology, formal analysis, visualization, writing – review and editing, and validation.

Funding Statement

This research was supported by the National Institute on Minority Health and Health Disparities of the National Institutes of Health (Award No. R01MD011277) and internal funds at Virginia Commonwealth University (VCU) for SPM’s doctoral research. The funder had no role in the design, data collection, data analysis, and reporting of this study.

Data Availability Statement

The data supporting this study’s findings are not publicly available due to privacy reasons but are available according to the Data User Agreement (DUA) policies set by the Centers for Medicare & Medicaid.

Supplementary Material.

References

  • 1. Michaud JM, Zhang T, Shireman TI, Lee Y, Wilson IB. Hazard of cervical, oropharyngeal, and anal cancers in HIV-infected and HIV-uninfected Medicaid beneficiaries. Cancer Epidemiol Biomarkers Prev. 2020;29(7):1447–57. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 2. Shiels MS, Pfeiffer RM, Gail MH, Hall HI, Li J, Chaturvedi AK, et al. Cancer burden in the HIV-infected population in the United States. J Natl Cancer Inst. 2011;103(9):753–62. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 3. Silverberg MJ, Lau B, Achenbach CJ, Jing Y, Althoff KN, D’Souza G, et al. Cumulative incidence of cancer among persons with HIV in North America: a cohort study. Ann Intern Med. 2015;163(7):507–18. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 4. Colón-López V, Shiels MS, Machin M, Ortiz AP, Strickler H, Castle PE, et al. Anal cancer risk among people with HIV infection in the United States. J Clin Orthod. 2018;36(1):68–75. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 5. Chiao EY, Krown SE, Stier EA, Schrag D. A population-based analysis of temporal trends in the incidence of squamous anal canal cancer in relation to the HIV epidemic. J Acquir Immune Defic Syndr. 2005;40(4):451–5. [DOI] [PubMed] [Google Scholar]
  • 6. Mitra S, Crane L. Diagnosis, treatment, and prevention of anal cancer. Curr Infect Dis Rep. 2012;14(1):61–6. [DOI] [PubMed] [Google Scholar]
  • 7. Johnson LG, Madeleine MM, Newcomer LM, Schwartz SM, Daling JR. Anal cancer incidence and survival: the surveillance, epidemiology, and end results experience, 1973–2000. Cancer. 2004;101(2):281–8. [DOI] [PubMed] [Google Scholar]
  • 8. Anal cancer: cancer stat facts. [Internet]. [cited 2018 Sep 8]. Available from: https://seer.cancer.gov/statfacts/html/anus.html#incidence-mortality
  • 9. Silverberg MJ, Lau B, Justice AC, Engels E, Gill MJ, Goedert JJ, et al. Risk of anal cancer in HIV-infected and HIV-uninfected individuals in North America. Clin Infect Dis. 2012;54(7):1026–34. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 10. Clifford GM, Georges D, Shiels MS, Engels EA, Albuquerque A, Poynten IM, et al. A meta-analysis of anal cancer incidence by risk group: toward a unified anal cancer risk scale. Int J Cancer. 2021;148(1):38–47. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 11. Palefsky JM, Holly EA, Hogeboom CJ, Ralston ML, DaCosta MM, Botts R, et al. Virologic, immunologic, and clinical parameters in the incidence and progression of anal squamous intraepithelial lesions in HIV-positive and HIV-negative homosexual men. J Acquir Immune Defic Syndr Hum Retrovirol. 1998;17(4):314–9. [DOI] [PubMed] [Google Scholar]
  • 12. Kreuter A, Potthoff A, Brockmeyer N, Gambichler T, Swoboda J, Stücker M, et al. Anal carcinoma in human immunodeficiency virus‐positive men: results of a prospective study from Germany. Br J Dermatol. 2010;162(6):1269–77. [DOI] [PubMed] [Google Scholar]
  • 13. Palefsky JM, Lee JY, Jay N, Goldstone SE, Darragh TM, Dunlevy HA, et al. Treatment of anal high-grade squamous intraepithelial lesions to prevent anal cancer. N Engl J Med. 2022;386(24):2273–82. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 14. Holly EA, Ralston ML, Darragh TM, Greenblatt RM, Jay N, Palefsky JM. Prevalence and risk factors for anal squamous intraepithelial lesions in women. J Natl Cancer Inst. 2001;93(11):843–9. [DOI] [PubMed] [Google Scholar]
  • 15. Moscicki A-B, Durako SJ, Houser J, Ma Y, Murphy DA, Darragh TM, et al. Human papillomavirus infection and abnormal cytology of the anus in HIV-infected and uninfected adolescents. AIDS. 2003;17(3):311–20. [DOI] [PubMed] [Google Scholar]
  • 16. Hessol NA, Holly EA, Efird JT, Minkoff H, Schowalter K, Darragh TM, et al. Anal intraepithelial neoplasia in a multisite study of HIV-infected and high-risk HIV-uninfected women. AIDS. 2009;23(1):59–70. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 17. Baranoski AS, Tandon R, Weinberg J, Huang FF, Stier EA. Risk factors for abnormal anal cytology over time in HIV-infected women. Obstet Gynecol. 2012;207(2):107. e1–8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 18. Gaisa M, Sigel K, Hand J, Goldstone S. High rates of anal dysplasia in HIV-infected men who have sex with men, women, and heterosexual men. AIDS. 2014;28(2):215–22. [DOI] [PubMed] [Google Scholar]
  • 19. Gaisa M, Ita-Nagy F, Sigel K, Arens Y, Hennessy MA, Rodriguez-Caprio G, et al. High rates of anal high-grade squamous intraepithelial lesions in HIV-infected women who do not meet screening guidelines. Clin Infect Dis. 2017;64(3):289–94. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 20. Wexler A, Berson AM, Goldstone SE, Waltzman R, Penzer J, Maisonet OG, et al. Invasive anal squamous-cell carcinoma in the HIV-positive patient: outcome in the era of highly active antiretroviral therapy. Dis Colon Rectum. 2008;51(1):73–81. [DOI] [PubMed] [Google Scholar]
  • 21. New York State Department of Health AIDS Institute . HIV clinical resource. Anal dysplasia and cancer guideline. 2007. [Internet] Available from: https://www.hivguidelines.org/adult-hiv/preventive-care-screening/anal-dysplasia-cancer/#tab_2 [Google Scholar]
  • 22. USPSTF/Veterans Administration . Anal dysplasia. 2016. [Internet] Available from: http://www.hiv.va.gov/provider/manual-primary-care/anal-dysplasia.asp
  • 23. Aberg JA, Kaplan JE, Libman H, Emmanuel P, Anderson JR, Stone VE, et al. Primary care guidelines for the management of persons infected with human immunodeficiency virus: 2009 update by the HIV medicine Association of the Infectious Diseases Society of America. Clin Infect Dis. 2009;49(5):651–81. [DOI] [PubMed] [Google Scholar]
  • 24. Cranston RD, Hart S, Gornbein J, Hirschowitz S, Cortina G, Moe A. The prevalence, and predictive value, of abnormal anal cytology to diagnose anal dysplasia in a population of HIV-positive men who have sex with men. Int J STD AIDS. 2007;18(2):77–80. [DOI] [PubMed] [Google Scholar]
  • 25. Berry JM, Palefsky JM, Jay N, Cheng SC, Darragh TM, Chin-Hong PV. Performance characteristics of anal cytology and human papillomavirus testing in patients with high-resolution anoscopy-guided biopsy of high-grade anal intraepithelial neoplasia. DisColon Rectum. 2009;52(2):239–47. [DOI] [PubMed] [Google Scholar]
  • 26. Kwong JJ, Cook P, Bradley-Springer L. Improving anal cancer screening in an ambulatory HIV clinic: experience from a quality improvement initiative. AIDS Patient Care STDS. 2011;25(2):73–8. [DOI] [PubMed] [Google Scholar]
  • 27. Scott H, Khoury J, Moore BA, Weissman S. Routine anal cytology screening for anal squamous intraepithelial lesions in an urban HIV clinic. Sex Transm Dis. 2008;35(2):197–202. [DOI] [PubMed] [Google Scholar]
  • 28. Palefsky JM, Holly EA, Hogeboom CJ, Berry JM, Jay N, Darragh TM. Anal cytology as a screening tool for anal squamous intraepithelial lesions. JAIDS JAcquired Immune DeficSyndromes. 1997;14(5):415–22. [DOI] [PubMed] [Google Scholar]
  • 29. Chung AP, Rosenfeld DB. Intraoperative high-resolution anoscopy: a minimally invasive approach in the treatment of patients with Bowen’s disease and results in a private practice setting. Am Surg. 2007;73(12):1279–83. [PubMed] [Google Scholar]
  • 30. Willeford WG, Barroso L, Keller J, Fino N, Bachmann LH. Anal dysplasia screening and treatment in a southern human immunodeficiency virus clinic. Sex Transm Dis. 2016;43(8):479–82. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 31. Durante AJ, Williams AB, Da Costa M, Darragh TM, Khoshnood K, Palefsky JM. Incidence of anal cytological abnormalities in a cohort of human immunodeficiency virus-infected women. Cancer Epidemiol Biomarkers Prev. 2003;12(7):638–42. [PubMed] [Google Scholar]
  • 32. Mathews WC, Sitapati A, Caperna JC, Barber RE, Tugend A, Go U. Measurement characteristics of anal cytology, histopathology, and high-resolution anoscopic visual impression in an anal dysplasia screening program. J Acquir Immune Defic Syndr. 2004;37:1610–5. [DOI] [PubMed] [Google Scholar]
  • 33. Weis SE, Vecino I, Pogoda JM, Susa JS, Nevoit J, Radaford D, et al. Prevalence of anal intraepithelial neoplasia defined by anal cytology screening and high-resolution anoscopy in a primary care population of HIV-infected men and women. Dis Colon Rectum. 2011;54(4):433–41. [DOI] [PubMed] [Google Scholar]
  • 34. Andersen R, Newman JF. Societal and individual determinants of medical care utilization in the United States. Milbank Mem Fund Q Health Soc. 2005;83(4). [PubMed] [Google Scholar]
  • 35. Kaiser Family Foundation . HIV/AIDS policy fact sheet: Medicaid and HIV/AIDS. 2013. [Internet] Available from: https://kaiserfamilyfoundation.files.wordpress.com/2013/03/7172-051.pdf
  • 36. Centers for Medicare and Medicaid Services . Medicaid analytic eXtract (MAX) general information. 2017. [Internet] Available from: https://www.cms.gov/Research-Statistics-Data-and-Systems/Computer-Data-and-Systems/MedicaidDataSourcesGenInfo/MAXGeneralInformation.html
  • 37. Barnett ML, Linder JA, Clark CR, Sommers BD. Low-value medical services in the safety-net population. JAMA Intern Med. 2017;177(6):829–37. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 38. Ding D, Glied SA. Are Medicaid patients seen in office-based practices getting high-quality primary care?. 2023. [Internet] [cited 2024 Mar 10]. Available from: https://www.commonwealthfund.org/publications/issue-briefs/2023/jan/medicaid-patients-office-practices-high-quality-primary-care
  • 39. Report | 2016 County Health Rankings Key Findings Report [Internet] . County Health Rankings & Roadmaps. [cited 2022 May 25]. Available from: https://www.countyhealthrankings.org/resources/2016-county-health-rankings-key-findings-report [Google Scholar]
  • 40. Bono RS, Dahman B, Sabik LM, Yerkes LE, Deng Y, Belgrave FZ, et al. Human immunodeficiency virus-experienced clinician workforce capacity: urban-rural disparities in the Southern United States. Clin Infect Dis. 2021;72(9):1615–22. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 41. Sommers BD, Gourevitch R, Maylone B, Blendon RJ, Epstein AM. Insurance churning rates for low-income adults under health reform: lower than expected but still harmful for many. Health Aff. 2016;35(10):1816–24. [DOI] [PubMed] [Google Scholar]
  • 42. Ku L, Steinmetz E. Bridging the gap: continuity and quality of coverage in Medicaid: George Washington University; 2013. [Internet] Available from: https://ccf.georgetown.edu/wp-content/uploads/2013/09/GW-Continuity-Report-9-10-13.pdf [Google Scholar]
  • 43. Leeds IL, Fang SH. Anal cancer and intraepithelial neoplasia screening: a review. World J Gastrointest Surg. 2016;8(1):41–51. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 44. Wellek S. A log-rank test for equivalence of two survivor functions. Biometrics. 1993;49(3):877–81. [PubMed] [Google Scholar]
  • 45. O’Brien RM. A caution regarding rules of thumb for variance inflation factors. Qual Quant. 2007;41(5):673–90. [Google Scholar]
  • 46. Tu N, Henderson M, Sundararajan M, Salas M. Discrepancies in ICD-9/ICD-10-based codes used to identify three common diseases in cancer patients in real-world settings and their implications for disease classification in breast cancer patients and patients without cancer: a literature review and descriptive study. Front Oncol. 2023;13:1016389. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 47. Wells JS, Holstad MM, Thomas T, Bruner DW. An integrative review of guidelines for anal cancer screening in HIV-infected persons. AIDS Patient Care STDS. 2014;28:350–7. [DOI] [PubMed] [Google Scholar]
  • 48. Chin-Hong PV, Palefsky JM. Natural history and clinical management of anal human papillomavirus disease in men and women infected with human immunodeficiency virus. Clin Infect Dis. 2002;35(9):1127–34. [DOI] [PubMed] [Google Scholar]
  • 49. Apaydin KZ, Fontenot HB, Shtasel DL, Mayer KH, Keuroghlian AS. Primary care provider practices and perceptions regarding HPV vaccination and anal cancer screening at a Boston community health center. J Community Health; 2018; p. 1–10. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 50. Reed AC, Reiter PL, Smith JS, Palefsky JM, Brewer NT. Gay and bisexual men’s willingness to receive anal Papanicolaou testing. AmJPublic Health. 2010;100(6):1123–9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 51. Rosa-Cunha I, DeGennaro VA, Hartmann R, Milikowski C, Irizarry A, Heitman B, et al. Description of a pilot anal pap smear screening program among individuals attending a Veteran’s Affairs HIV clinic. AIDS Patient Care STDS. 2011;25(4):213–9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 52. D’souza G, Rajan SD, Bhatia R, Cranston RD, Plankey MW, Silvestre A, et al. Uptake and predictors of anal cancer screening in men who have sex with men. AmJPublic Health. 2013;103(9):e88–95. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 53. Ea S, Ma C, Aa D, N W, Y L, Im P, et al. International Anal Neoplasia Society’s consensus guidelines for anal cancer screening. Int J Cancer. 2024. [Internet] [cited 2025 Feb 16];154. Available from: https://pubmed.ncbi.nlm.nih.gov/38297406/ [DOI] [PubMed] [Google Scholar]
  • 54. Roberts JR, Siekas LL, Kaz AM. Anal intraepithelial neoplasia: a review of diagnosis and management. World J Gastrointest Oncol. 2017;9(2):50–61. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 55. University of California Frascisco San . DARE and HRA Anal cancer information. Anal Cancer Information; 2014. Internet [cited 2018 Oct 28]. Available from: https://analcancerinfo.ucsf.edu/dare-and-hra [Google Scholar]
  • 56. Palefsky JM. Practising high-resolution anoscopy. Sex Health. 2012;9:580–6. [DOI] [PubMed] [Google Scholar]
  • 57. Richel O, Prins JM, de Vries HJ. Screening for anal cancer precursors: what is the learning curve for high-resolution anoscopy? AIDS. 2014;28(9):1376–7. [DOI] [PubMed] [Google Scholar]
  • 58. Cook JA, Burke-Miller JK, Grey DD, Cocohoba J, Liu C, Schwartz RM, et al. Do HIV-positive women receive depression treatment that meets best practice guidelines? AIDS Behav. 2014;18(6):1094–102. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 59. Barnes A, Betts AC, Borton EK, Sanders JM, Pruitt SL, Werner C, et al. Cervical cancer screening among HIV-infected women in an urban, United States safety-net healthcare system. AIDS. 2018;32(13):1861–70. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 60. Gaither JR, Goulet JL, Becker WC, Crystal S, Edelman EJ, Gordon K, et al. Guideline-concordant management of opioid therapy among human immunodeficiency virus (HIV)-infected and uninfected veterans. J Pain. 2014;15(11):1130–40. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 61. Kilbourne AM, Asch S, Andersen RM, Nakazono T, Gifford AL, Bozzette SA, et al. Development and application of a method to assess timeliness of medical care for HIV symptoms. Health Servoutcomes Res. 2001;2:101–15. [Google Scholar]
  • 62. Torian LV, Wiewel EW. Continuity of HIV-related medical care, New York City, 2005–2009: do patients who initiate care stay in care? AIDS Patient Care STDS. 2011;25(2):79–88. [DOI] [PubMed] [Google Scholar]
  • 63. Mugavero MJ, Lin HY, Allison JJ, Giordano TP, Willig JH, Raper JL, et al. Racial disparities in HIV virologic failure: do missed visits matter? J Acquir Immune Defic Syndr. 2009;50(1):100–8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 64. Stone VE. Optimizing the care of minority patients with HIV/AIDS. Clin Infect Dis. 2004;38(3):400–4. [DOI] [PubMed] [Google Scholar]
  • 65. Wilson LE, Korthuis T, Fleishman JA, Conviser R, Lawrence PB, Moore RD, et al. HIV-related medical service use by rural/urban residents: a multistate perspective. AIDS Care. 2011;23(8):971–9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 66. Suneja G, Shiels MS, Angulo R, Copeland GE, Gonsalves L, Hakenewerth AM, et al. Cancer treatment disparities in HIV-infected individuals in the United States. J Clin Oncol. 2014;32(22):2344–50. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 67. Deeken JF, Tjen-A-Looi A, Rudek MA, Okuliar C, Young M, Little RF, et al. The rising challenge of non-AIDS-defining cancers in HIV-infected patients. Clin Infect Dis. 2012;55(9):1228–35. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 68. Bower M, Collins S, Cottrill C, Cwynarski K, Montoto S, Nelson M, et al. British HIV Association guidelines for HIV-associated malignancies 2008. HIV Med. 2008;9(6):336–88. [DOI] [PubMed] [Google Scholar]
  • 69. Mark Freedman DMPH, John Weiser MMPH, Linda R, Beer PR, Luke Shouse MMPH. Anal cancer screening in men who have sex with men in care for HIV infection: United States; 2009–2012. [Internet]. 2016. Available from: https://idsa.confex.com/idsa/2016/webprogram/Paper56203.html [Google Scholar]
  • 70. Mathematica Policy Research . Medicaid managed care enrollment and program characteristics; 2016. [Internet]. 2018. Available from: https://www.medicaid.gov/medicaid/managed-care/downloads/enrollment/2016-medicaid-managed-care-enrollment-report.pdf [Google Scholar]
  • 71. Gorbach PM, Manhart LE, Hess KL, Stoner BP, Martin DH, Holmes KK. Anal intercourse among young heterosexuals in three sexually transmitted disease clinics in the United States. Sex Transm Dis. 2009;36(4):193–8. [DOI] [PMC free article] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Supplementary_material-Suppl.1-s1.docx (4.2MB, docx)

Data Availability Statement

The data supporting this study’s findings are not publicly available due to privacy reasons but are available according to the Data User Agreement (DUA) policies set by the Centers for Medicare & Medicaid.

Articles from Oncology Research and Treatment are provided here courtesy of Karger Publishers

RESOURCES