Abstract
Background.
Home-based self-sampling may be a viable option for anal cancer screening among sexual minority men (SMM). Yet limited research has compared home-based self-collected with clinician-collected anal swabs for human papillomavirus (HPV) genotyping.
Methods.
The Prevent Anal Cancer Self-Swab Study recruited SMM and transgender persons 25 years and over in Milwaukee, Wisconsin, USA to participate in an anal cancer screening study. Participants were randomized to a home or clinic arm. Home-based participants were mailed an anal self-sampling kit to complete and return via postal mail. They were also asked to attend a clinic appointment where a clinician collected an anal swab. Swabs were HPV-genotyped using the SPF10-LiPA25 assay. We analyzed 79 paired self and clinician swabs to determine HPV prevalence, percent agreement, and sensitivity and specificity of the mailed home-based anal self-swab to detect HPV genotypes using the clinician-collected swab as the reference.
Results.
The median number of days between the home and clinic swab was 19 days (range=2 to 70). HPV was detected in 73.3% of self and 75.0% of clinician anal swabs (p=.99). Prevalence of any HPV, any high-risk HPV, any low-risk HPV, and individual HPV types did not significantly differ between self and clinician anal swabs. Agreement between self and clinician swabs was over 90% for 21 of the 25 HPV genotypes. Mailed home-based self-collected swabs had a sensitivity of 94.1% (95% CI: 82.9 – 99.0) for detection of high-risk HPV versus clinician-collected sampling.
Conclusions.
Mailed home-based self-collected and clinician-collected anal swabs demonstrated high concordance for HPV genotyping.
Keywords: human papillomavirus (HPV), anal cancer, self-sampling, sexual minority men (SMM), screening
Summary:
Mailed home self-collected and clinician-collected clinic anal swabs demonstrated high concordance for HPV genotyping among sexual minority men and trans persons. Agreement was over 90% for 21 of 25 genotypes.
Introduction
Anal cancer has disproportionately high incidence among sexual minority men (SMM) living with HIV (1). Although there is not yet a consensus screening guideline for anal cancer, one possible method to screen is human papillomavirus (HPV) testing. Anal cancer is largely associated with persistent oncogenic HPV infection. Most anal cancer cases are attributable to HPV infection, with HPV 16 and 18 responsible for 87 percent of anal cancer cases worldwide (2). Much like HPV self-sampling for cervical cancer screening, anal HPV self-sampling for detection of high-risk HPV genotypes could be a potential method to screen for anal precancer. Research has shown high acceptability of anal self-sampling among men who have sex with men (3). Home-based anal HPV self-sampling has significantly higher screening engagement among black SMM and SMM living with HIV, two groups at highest risk for anal cancer (4).
Although HPV testing for cervical cancer screening has demonstrated high agreement between self and clinician samples (5), limited studies have examined this topic for anal swabs collected by SMM. Obtaining a self-sample from the anal canal may present different challenges than those encountered in cervicovaginal sampling. For example, fecal matter in the anal canal may produce inadequate results for HPV genotyping (6). There are also important anatomical differences from the cervix, such as mucosal folds in the anal canal which can hide lesions (7). Clinicians and lay persons may position and swab the anal canal at different angles, which could affect the collection and detection of HPV genotypes.
Previous research has compared HPV genotypes in self and clinician anorectal swabs among SMM collecting a self-swab in a clinic (8–10). Studies have also compared self and clinician anal cytology specimens (11, 12). However, no studies to our knowledge have compared clinician-collected swabs with home-based anal HPV self-swabs returned through the postal mail. If self-collected sampling for anal cancer screening is to be implemented, research is needed on real-world comparisons between clinician-collected anal swabs and home-based self-collected anal swabs traveling through the mail. To that end, the present study utilizes paired self and clinician swabs from the same person to compare HPV genotypes present in self-swabs collected in the home via a mailed anal self-sampling kit.
Materials and Methods
Study recruitment and design
The Prevent Anal Cancer Self-Swab Study recruited sexual and gender minority individuals in the Milwaukee, Wisconsin metropolitan area to participate in an anal cancer screening study. A detailed description of the study protocol has been published elsewhere(13). In brief, recruitment methods included social media advertisements, promotional materials in targeted businesses and nonprofits, community groups, clinic waiting groups, and a voluntary referral program. Interested individuals completed an eligibility survey via REDCap. Eligibility criteria included: age 25 years or older, assigned male sex at birth or reported gender identity as transgender, reported sex with men in the last five years or identified as gay or bisexual, and reported no prior anal cancer diagnosis. Informed consent was obtained from study participants and study activities were approved by the Medical College of Wisconsin Human Protections Committee.
Participants were randomized in a one-to-one allocation to either a home or clinic study arm. This analysis utilizes baseline data from home-based participants only, given that participants in the clinic study arm were not offered self-collection. In the home-based arm, participants were mailed an anal self-sampling kit. The kit contained a flocked swab with a “stopper”, or flared section, on the handle to indicate how far to insert the swab into the anus (COPAN Italia S.p.A., Brescia, Italy), a vial of standard transport media (QIAGEN, Germantown, MD, USA), and illustrated instructions written at a sixth-grade reading level in English or Spanish patterned after similar published instructions(14). The instructions asked participants to wash their hands, get into a comfortable position, gently push the swab into their anus up to the flared section, or “stopper”, and then to move the swab in a circle and to press against the walls of the anus while counting slowly to ten (see Supplemental Figure 1 in Supplemental Digital Content). The kit also included return packaging and illustrated instructions for returning the sample. A phone number was provided for participants to contact with any questions about the kit. Participants were asked to mail the completed swab via postage-paid packaging overnight to the Medical College of Wisconsin Tissue Bank for processing.
Home-based participants were also asked to attend a study clinic of their choice to rule out prevalent anal cancer since it was an exclusion criterion. During this appointment, a trained clinician collected an anal swab from the participant and then performed a digital anal rectal exam. Study staff placed the swabs into an insulated cooler and returned them to the Medical College of Wisconsin Tissue Bank for processing.
Instructions for collecting the sample were the same for both home and clinic and utilized the Darragh swabbing protocol (e.g., twirl the swab while pressing against the anal canal walls, count slowly to 10, etc.) (15). Swabs used in the home and clinic were also identical (COPAN Italia S.p.A., Brescia, Italy). All specimens were sent to Moffitt Cancer Center and Research Institute for DNA extraction and HPV genotyping. The SPF10-LiPA25 assay was used for HPV genotyping which included 15 high-risk HPV types (16, 18, 31, 33, 35, 39, 45, 51, 52, 53, 56, 58, 59, 66, 68/73) and 10 low-risk HPV types (6, 11, 34, 40, 42, 43, 44, 54, 70, 74).
Study sample
Between January 2020 and August 2022, a total of 120 participants were randomized to the home-based screening arm (due to the COVID pandemic, study activities were suspended between March and November 2020). Of those 120 home-based participants, 79 individuals completed both a self- and clinician-collected anal swab at baseline. If one of the paired swabs was inadequate or untypable, the participant was excluded from analysis. Swabs were judged inadequate when the assay did not detect the housekeeping gene human RNase P. An untypable result meant that the assay detected HPV DNA that was not one of the 25 genotypes included in the SPF10-LiPA25 assay. A total of 7 swabs were inadequate for HPV genotyping (5 self, 1 clinician, and 1 both self and clinician) and 7 swabs detected untypable HPV (5 self, 2 clinician). This resulted in 65 participants. We limited the analysis to swabs taken less than or equal to 10 weeks apart, which resulted in 60 participants with paired self and clinician anal swabs. We excluded five participants from analysis due to long periods of time between their home and clinic swabs (range: 102 to 355 days). Participant characteristics such as age, race/ethnicity, and HIV status were self-reported during the eligibility and baseline survey.
Statistical analysis
Descriptive statistics were conducted for participant demographic characteristics and HPV prevalence (any HPV, any high-risk HPV, any low-risk HPV, any of the 9-valent vaccine HPV genotypes, and the 25 HPV genotypes in the SPF10-LiPA25 assay). McNemar exact tests (2-tailed) using the binomial distribution were used to compare HPV prevalence in paired self and clinician swabs. Percent agreement between self and clinician swabs was calculated for each HPV genotype. Self and clinician swabs were considered in agreement if both were positive for the same HPV genotype(s), or both were negative for the HPV genotype(s). We also examined whether agreement differed by HIV status and HPV vaccination using chi-square tests of association.
Sensitivity and specificity were calculated using the clinician-collected swab as the gold standard. Since we do not assess clinical disease outcomes in this analysis, sensitivity and specificity results refer to analytic sensitivity and specificity rather than clinical diagnostic sensitivity and specificity. Profile likelihood 95% confidence intervals were calculated for the sensitivity and specificity analyses. Supplementary analyses were also conducted using the full sample of all paired home self-collected and clinician-collected clinic anal swabs. Inadequate specimens and swabs with untypable HPV were compared between home and clinic. We then re-ran all analyses using all adequate, typable paired swabs to examine whether time between the home and clinic swab affected the results.
All statistical analyses were conducted in SPSS (16).
Results
The median age of participants was 49 and ranged from 27 to 78 years old (Table 1). Approximately two-thirds (66.1%) of the sample identified as non-Hispanic white, 18.6% identified as non-Hispanic black, and 15.3% identified as Hispanic or Latino. Nearly all participants (95%) identified as a man and 5.0% identified as trans or non-binary. A total of 86.7% of sample participants identified as gay and 13.3% identified as bisexual or queer. Just over one in four (26.7%) participants were living with HIV. Most of the sample (68.3%) had 16 or more years of education. A total of 13.3% reported ever having had the HPV vaccine.
Table 1.
Characteristics of 60 participants who completed a baseline self-swab and clinician swab in the Prevent Anal Cancer Self-Swab Study, 2020–2022, Milwaukee, Wisconsin, USA.
| n (%) | |
|---|---|
| Age, years Median, Range | 49, 27 – 78 |
| 25–34 | 17 (28.3) |
| 35–44 | 9 (15.0) |
| 45–54 | 9 (15.0) |
| 55+ | 25 (41.7) |
| Race/ethnicity | |
| White, non-Hispanic | 39 (66.1) |
| Black, non-Hispanic | 11 (18.6) |
| Hispanic or Latino | 9 (15.3) |
| Missing | 1 |
| Gender identity | |
| Man | 57 (95.0) |
| Trans woman or non-binary | 3 (5.0) |
| Sexual orientation | |
| Gay | 52 (86.7) |
| Bisexual or queer | 8 (13.3) |
| HIV status | |
| Positive | 16 (26.7) |
| Negative | 44 (73.3) |
| Education | |
| 12 years | 4 (6.7) |
| 13–15 years | 15 (25.0) |
| 16 years | 17 (28.3) |
| More than 16 years | 24 (40.0) |
| Ever received HPV vaccine | |
| Yes | 8 (13.3) |
| No | 32 (53.3) |
| I don’t know | 20 (33.3) |
Abbreviations: HPV, human papillomavirus.
Prevalence of any HPV, any high-risk HPV, any low-risk HPV, and any HPV types present in the 9-valent vaccine did not significantly differ between self and clinician anal swabs (Figure 1). A total of 73.3% of self-collected anal swabs and 75% of clinician-collected anal swabs tested positive for any of the 25 HPV genotypes in the SPF10-LiPA25 assay (p=.99). A higher proportion of self-collected anal swabs tested positive for any of the high-risk HPV genotypes (65.0%) compared to clinician-collected swabs (56.7%), but this difference was not significant (p=.18).
Figure 1.
HPV prevalence among 60 paired self and clinician anal swabs in the Prevent Anal Cancer Self-Swab Study, Milwaukee, WI, USA, 2020–2022.
Note. McNemar exact test (2-tailed) using the binomial distribution.
Abbreviations: HPV, human papillomavirus. High-risk HPV types: 16, 18, 31, 33, 35, 39, 45, 51, 52, 53, 56, 58, 59, 66, and 68/73. Low-risk HPV types: 6, 11, 34, 40, 42, 43, 44, 54, 70, and 74.
Results of McNemar tests did not show any significant difference between self and clinician swabs for any of the 25 HPV genotypes (Table 2). The most prevalent HPV genotypes detected in both self and clinician swabs were HPV 31, HPV 52, HPV 53, HPV 6, and HPV 16. Self-collected anal swabs had the highest prevalence of HPV 52 (20.0%), followed by HPV 31 (18.3%), HPV 53% (15.0%), HPV 6 (13.3%), and HPV 16 (11.7%). Clinician-collected anal swabs had the highest prevalence of HPV 53 (18.3%), followed by HPV 6 (16.7%), HPV 16 (13.3%), HPV 31 (13.3%), and HPV 52 (11.7%). Overall, percent agreement was above 86% for all 25 HPV genotypes (Table 3). Over half (56%) of the HPV genotypes had percent agreement between 96% and 100%. No significant differences in HPV agreement were found by HIV status or HPV vaccination for self- or clinician-collected swabs (data not shown).
Table 2.
Comparison of 60 paired self-collected vs. clinician-collected anal swabs in the Prevent Anal Cancer Self-Swab Study, Milwaukee, Wisconsin, USA, 2020–2022.
| Self-collected | Clinician-collected | ||
|---|---|---|---|
| n (%) | n (%) | p-value1 | |
| High-risk HPV types | |||
| HPV 16 | 0.99 | ||
| Yes | 7 (11.7) | 8 (13.3) | |
| No | 53 (88.3) | 52 (86.7) | |
| HPV 18 | 0.50 | ||
| Yes | 1 (1.7) | 3 (5.0) | |
| No | 59 (98.3) | 57 (95.0) | |
| HPV 31 | 0.45 | ||
| Yes | 11 (18.3) | 8 (13.3) | |
| No | 49 (81.7) | 52 (86.7) | |
| HPV 33 | 0.99 | ||
| Yes | 4 (6.7) | 3 (5.0) | |
| No | 56 (93.3) | 57 (95.0) | |
| HPV 35 | 0.99 | ||
| Yes | 4 (6.7) | 3 (5.0) | |
| No | 56 (93.3) | 57 (95.0) | |
| HPV 39 | 0.25 | ||
| Yes | 4 (6.7) | 1 (1.7) | |
| No | 56 (93.3) | 59 (98.3) | |
| HPV 45 | 0.99 | ||
| Yes | 1 (1.7) | 1 (1.7) | |
| No | 59 (98.3) | 59 (98.3) | |
| HPV 51 | 0.99 | ||
| Yes | 6 (10.0) | 6 (10.0) | |
| No | 54 (90.0) | 54 (90.0) | |
| HPV 52 | 0.13 | ||
| Yes | 12 (20.0) | 7 (11.7) | |
| No | 48 (80.0) | 53 (88.3) | |
| HPV 53 | 0.63 | ||
| Yes | 9 (15.0) | 11 (18.3) | |
| No | 51 (85.0) | 49 (81.7) | |
| HPV 56 | 0.99 | ||
| Yes | 5 (8.3) | 5 (8.3) | |
| No | 55 (91.7) | 55 (91.7) | |
| HPV 58 | 0.50 | ||
| Yes | 2 (3.3) | -- | |
| No | 58 (96.7) | 60 (100.0) | |
| HPV 59 | 0.99 | ||
| Yes | 2 (3.3) | 3 (5.0) | |
| No | 58 (96.7) | 57 (95.0) | |
| HPV 66 | 0.99 | ||
| Yes | 1 (1.7) | -- | |
| No | 59 (98.3) | 60 (100.0) | |
| HPV 68/73 | 0.99 | ||
| Yes | 2 (3.3) | 3 (5.0) | |
| No | 58 (96.7) | 57 (95.0) | |
| Low-risk HPV types | |||
| HPV 6 | 0.69 | ||
| Yes | 8 (13.3) | 10 (16.7) | |
| No | 52 (86.7) | 50 (83.3) | |
| HPV 11 | 0.50 | ||
| Yes | 3 (5.0) | 1 (1.7) | |
| No | 57 (95.0) | 59 (98.3) | |
| HPV 34 | -- | ||
| Yes | -- | -- | |
| No | 60 (100.0) | 60 (100.0) | |
| HPV 40 | 0.99 | ||
| Yes | 1 (1.7) | 1 (1.7) | |
| No | 59 (98.3) | 59 (98.3) | |
| HPV 42 | 0.99 | ||
| Yes | 1 (1.7) | -- | |
| No | 59 (98.3) | 60 (100.0) | |
| HPV 43 | 0.99 | ||
| Yes | 1 (1.7) | 1 (1.7) | |
| No | 59 (98.3) | 59 (98.3) | |
| HPV 44 | 0.25 | ||
| Yes | 3 (5.0) | 6 (10.0) | |
| No | 57 (95.0) | 54 (90.0) | |
| HPV 54 | 0.99 | ||
| Yes | 1 (1.7) | 1 (1.7) | |
| No | 59 (98.3) | 59 (98.3) | |
| HPV 70 | 0.99 | ||
| Yes | 6 (10.0) | 7 (11.7) | |
| No | 54 (90.0) | 53 (88.3) | |
| HPV 74 | 0.63 | ||
| Yes | 1 (1.7) | 3 (5.0) | |
| No | 59 (98.3) | 57 (95.0) |
Abbreviations: HPV, human papillomavirus.
McNemar exact test (2-tailed) using the binomial distribution.
Table 3.
Percent agreement of 60 paired self-collected and clinician-collected anal swabs for individual HPV genotypes in the Prevent Anal Cancer Self-Swab Study, Milwaukee, Wisconsin, USA, 2020–2022.
| % Agreement1 | High-risk HPV types | Low-risk HPV types |
|---|---|---|
| 86–90% | 31, 51, 52 | 6 |
| 91–95% | 16, 39, 53, 59 | 44, 70, 74 |
| 96–100% | 18, 33, 35, 45, 56, 58, 66, 68/73 | 11, 34, 40, 42, 43, 54 |
Agreement = both self and clinician swabs are positive for that HPV type or negative for that HPV type.
Abbreviations: HPV, human papillomavirus.
Results of sensitivity and specificity analyses for HPV infection endpoints using the clinician-collected anal swab test results as the reference are provided in Table 4. Detection of any HPV by the self-collected swab had a sensitivity of 88.9% (95% CI: 77.6 – 95.9) and specificity of 73.3% (95% CI: 48.5 – 90.8). Self-collected swabs had a sensitivity of 94.1% (95%: CI 82.9 – 99.0) and specificity of 73.1% (95% CI: 54.4 – 87.4) to detect any of the high-risk HPV types. The sensitivity of the self-collected swabs to detect any of the low-risk HPV types was 75.9% (95% CI: 58.5 – 88.8) and specificity was 90.3% (95% CI: 76.8 – 97.5).
Table 4.
Analytic sensitivity and specificity analyses of 60 paired self-collected vs. clinician-collected anal swabs in the Prevent Anal Cancer Self-Swab Study, Milwaukee, Wisconsin, USA, 2020–2022.
| Any HPV | |||||
|---|---|---|---|---|---|
| Clinician (reference) | |||||
| Negative | Positive | Total | Sensitivity of Self | Specificity of Self | |
| n (%) | n (%) | n (%) | % (95% CI) | % (95% CI) | |
| Self | 88.9 (77.6 – 95.9) | 73.3 (48.5 – 90.8) | |||
| Negative | 11 (73.3) | 5 (11.1) | 16 (26.7) | ||
| Positive | 4 (26.7) | 40 (88.9) | 44 (73.3) | ||
| Total | 15 (100.0) | 45 (100.0) | 60 (100.0) | ||
| Any high-risk HPV | |||||
| Clinician (reference) | |||||
| Negative | Positive | Total | Sensitivity of Self | Specificity of Self | |
| n (%) | n (%) | n (%) | % (95% CI) | % (95% CI) | |
| Self | 94.1 (82.9 – 99.0) | 73.1 (54.4 – 87.4) | |||
| Negative | 19 (73.1) | 2 (5.9) | 21 (35.0) | ||
| Positive | 7 (26.9) | 32 (94.1) | 39 (65.0) | ||
| Total | 26 (100.0) | 34 (100.0) | 60 (100.0) | ||
| Any low-risk HPV | |||||
| Clinician (reference) | |||||
| Negative | Positive | Total | Sensitivity of Self | Specificity of Self | |
| n (%) | n (%) | n (%) | % (95% CI) | % (95% CI) | |
| Self | 75.9 (58.5 – 88.8) | 90.3 (76.8 – 97.5) | |||
| Negative | 28 (90.3) | 7 (24.1) | 35 (58.3) | ||
| Positive | 3 (9.7) | 22 (75.9) | 25 (41.7) | ||
| Total | 31 (100.0) | 29 (100.0) | 60 (100.0) | ||
Note. Clinician-collected anal swab test results were used as the reference.
Abbreviations: HPV, human papillomavirus. High-risk HPV types: 16, 18, 31, 33, 35, 39, 45, 51, 52, 53, 56, 58, 59, 66, and 68/73. Low-risk HPV types: 6, 11, 34, 40, 42, 43, 44, 54, 70, and 74.
Specimen adequacy and presence of untypable HPV did not differ significantly between self-collected and clinician-collected anal swabs (see Supplemental Table 1 in Supplemental Digital Content). Supplemental analyses using the full sample of all paired swabs not limited by time criteria yielded similar findings, with no significant differences found between home and clinic swabs in terms of HPV prevalence, concordance, or agreement by HIV status and HPV vaccination (see Supplemental Tables 2 and 3). The only exception was that HPV 52 prevalence in the full sample of all paired swabs not limited by time criteria differed between self-collected (21.5%) and clinician-collected (10.8%) swabs (p=.04) (see Supplemental Table 2 in Supplemental Digital Content). Specificity using the full sample of all paired swabs with no time criteria imposed was nearly identical and specificity was similar (see Supplemental Table 4 in Supplemental Digital Content).
Discussion
This is the first research to our knowledge to compare clinician swabs with mailed home-based anal swabs for HPV genotyping. We utilized self and clinician anal swabs obtained from the same person to examine HPV genotyping concordance. Overall, agreement was high. There were no significant differences between self and clinician swabs for any of the 25 HPV genotypes in the SPF10-LiPA25 assay. Percent agreement between self and clinician swabs was above 86% for all 25 HPV genotypes, and between 96% and 100% for over half of the HPV genotypes.
The most prevalent HPV genotypes detected in both self and clinician swabs were HPV 31, HPV 52, HPV 53, HPV 6, and HPV 16. Apart from HPV 6, which is associated with warts, these are all high-risk HPV genotypes. Using the clinician-collected anal swab as the reference, mailed home-based self-collected swabs had a sensitivity of 94.1% and specificity of 73.1% to detect any of the high-risk HPV types. This is important because HPV 16, one of the high-risk HPV types, is responsible for most anal cancer cases worldwide (2).
A major strength of this research is that we compared clinician-collected anal swabs with mailed home-based self-collected anal swabs. If at-home HPV testing is to be implemented as an option for anal cancer screening, data on swabs in a real-world context are needed. In another analysis from the Prevent Anal Cancer Self-Swab Study, we found that environmental conditions such as temperature and travel time were not associated with home-based anal swab specimen adequacy (6). We also found that swabs obtained from home-based anal self-sampling have comparable adequacy to clinician-collected specimens (4). Our findings from this research showed no difference in HPV genotyping between mailed home-based self-swabs and clinician-collected swabs.
There were also no significant differences in HPV agreement by HIV status or HPV vaccination status. We have previously found that home-based anal self-sampling has higher screening engagement among black SMM and SMM living with HIV, which are two groups disproportionately affected by anal cancer (4). Home-based anal HPV self-sampling produces adequate specimens that are comparable to clinician-collected specimens and has high engagement among SMM. Taken together, these findings show that home-based anal self-sampling could be a potential option to reach groups at higher risk for anal cancer.
Since this research was an ancillary analysis of the Prevent Anal Cancer Self-Swab Study, self and clinician swabs were not collected on the same day. We limited our analysis to swabs collected less than or equal to 10 weeks apart. Ideally, concordance could be assessed between clinician swabs and mailed home-based self-swabs collected on the same day. Despite this limitation, we still found high concordance and agreement between mailed home-based anal self-swabs and clinician-collected swabs taken at a clinic appointment. Supplementary analyses using all swabs not limited to this time criterion also showed similar results. Our results provide a real-world example of anal cancer screening using home-based anal self-sampling. However, it is important to note that this research used the SPF10-LiPA25 assay which is very sensitive. It is possible that screening programs might use a less sensitive assay. We also examined analytic infection endpoints only, not clinical disease outcomes. The utility of HPV testing in screening for anal precancers is currently being studied.
It is important to note that the sample size may have limited statistical power and thus the ability to detect differences between lay-sampled and clinician-sampled genotypes. In some cases, the self-sample failed to detect a genotype that was positive in the clinician swab and vice versa. Future research using larger sample sizes of paired specimens is needed to address these limitations.
To conclude, we found that home-based anal HPV self-sampling is comparable to clinician-collected HPV anal sampling. Percent agreement of HPV genotypes was high, with no significant differences between self and clinician swabs. There was also no difference by HIV status or HPV vaccination status. Home-based anal self-sampling represents a viable option for anal cancer screening with the potential to reach those who are disproportionately affected by anal cancer.
Supplementary Material
Supplemental Figure 1. Mailed home-based anal HPV self-sampling kit (PAC Pack) illustrated instructions from the Prevent Anal Cancer Self-Swab Study, Milwaukee, Wisconsin, USA, 2020–2022.
Supplemental Table 1. Comparison of paired self and clinician anal swabs by specimen adequacy and typable HPV in the Prevent Anal Cancer Self-Swab Study, Milwaukee, Wisconsin, USA, 2020–2022.
Supplemental Table 2. Comparison of 65 paired self and clinician anal swabs in the Prevent Anal Cancer Self-Swab Study, Milwaukee, Wisconsin, USA, 2020–2022.
Supplemental Table 3. Percent agreement of 65 paired self-collected and clinician-collected anal swabs for individual HPV genotypes in the Prevent Anal Cancer Self-Swab Study, Milwaukee, Wisconsin, USA, 2020–2022.
Supplemental Table 4. Analytic sensitivity and specificity analyses of 65 paired self-collected vs. clinician-collected anal swabs in the Prevent Anal Cancer Self-Swab Study, Milwaukee, Wisconsin, USA, 2020–2022.
Acknowledgements:
Thank you to all the study participants and the PAC Study Team (Bridgett Brzezinski, Cameron Liebert, Esmeralda Lezama-Ruiz, Madison Humphry, Maritza Pallo, and Christopher Ajala). We also thank COPAN Italia S.p.A. for donating some of the swabs used in this study. We are grateful to the University of Chicago for help with the illustrated instructions for self-collection.
Conflicts of Interest and Source of Funding:
The authors have no conflicts of interests to declare. This clinical trial was supported by the National Cancer Institute of the National Institutes of Health (grant number R01CA215403 to AGN) and Clinical and Translational Science Institute grant support (2UL1TR001436). These funding entities were not involved in the design, collection, analysis, or interpretation of data, writing, or decision to submit this research for publication. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Data Availability Statement:
Fully de-identified datasets and data dictionary will be shared with properly trained investigators on the study website (https://mindyourbehind.org) within one year of study completion after assessment of institutional policies, Medical College of Wisconsin Human Research Protections Program rules, as well as local, state, and federal laws and regulations. Further information is available from Dr. Alan G. Nyitray (anyitray@mcw.edu) upon request.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Supplemental Figure 1. Mailed home-based anal HPV self-sampling kit (PAC Pack) illustrated instructions from the Prevent Anal Cancer Self-Swab Study, Milwaukee, Wisconsin, USA, 2020–2022.
Supplemental Table 1. Comparison of paired self and clinician anal swabs by specimen adequacy and typable HPV in the Prevent Anal Cancer Self-Swab Study, Milwaukee, Wisconsin, USA, 2020–2022.
Supplemental Table 2. Comparison of 65 paired self and clinician anal swabs in the Prevent Anal Cancer Self-Swab Study, Milwaukee, Wisconsin, USA, 2020–2022.
Supplemental Table 3. Percent agreement of 65 paired self-collected and clinician-collected anal swabs for individual HPV genotypes in the Prevent Anal Cancer Self-Swab Study, Milwaukee, Wisconsin, USA, 2020–2022.
Supplemental Table 4. Analytic sensitivity and specificity analyses of 65 paired self-collected vs. clinician-collected anal swabs in the Prevent Anal Cancer Self-Swab Study, Milwaukee, Wisconsin, USA, 2020–2022.
Data Availability Statement
Fully de-identified datasets and data dictionary will be shared with properly trained investigators on the study website (https://mindyourbehind.org) within one year of study completion after assessment of institutional policies, Medical College of Wisconsin Human Research Protections Program rules, as well as local, state, and federal laws and regulations. Further information is available from Dr. Alan G. Nyitray (anyitray@mcw.edu) upon request.