The accuracy of anal self- and companion exams among sexual minority men and transgender women: a prospective analysis

Abstract

Background: Squamous cell carcinoma of the anus (SCCA) annual incidence among sexual minority men with and without HIV is 85/100,000 and 19/100,000 persons, respectively, which is significantly higher than the overall incidence (2/100,000). Incidence may also be higher in transgender women. Since SCCA tumours average ≥30 mm at diagnosis, we assessed the accuracy of individuals to self-detect smaller anal abnormalities.

Methods: Using convenience sampling, the study enrolled sexual minority men and transgender women, aged 25-81 years, in Chicago, Illinois and Houston, Texas, USA, during 2020-2022. Individuals were taught the anal self-examination and anal companion examination (ASE/ACE). Then, a clinician performed a digital anal rectal examination (DARE) before participants conducted the ASE or ACE. The sensitivity, specificity and concordance of the ASE/ACE to detect an abnormality were measured along with factors associated with ASE/ACE and DARE concordance.

Findings: Among 714 enrolled individuals, the median age was 40 years (interquartile range, 32-54), 36.8% (259/703) were living with HIV, and 47.0% (334/710), 23.4% (166/710), and 23.0% (163/710) were non-Hispanic white, non-Hispanic Black, and Hispanic, respectively. A total of 94.1% (671/713) identified as cisgendered men, and 5.9% (42/713) as gender minorities. A total of 658 participants completed an ASE and 28 couples (56 partners) completed an ACE. Clinicians detected abnormalities in 34.3% (245/714) of individuals. The abnormalities were a median of 3 mm in diameter. Sensitivity and specificity of the ASE/ACE was 59.6% (95% CI 53.5-65.7%) and 80.2% (95% CI 76.6-83.8%), respectively. Overall concordance was 0.73 (95% CI 0.70-0.76) between ASE/ACE and DARE and increased with increasing anal canal lesion size (p = 0.02). Concordance was lower when participants were older and received ASE/ACE training from a lay person rather than a clinician.

Interpretation: Sexual minority men/transgender women may self-detect SCCA when malignant lesions are much smaller than the current mean dimension at presentation of ≥30 mm.

Funding: National Cancer Institute.

Keywords: Anal canal; Anus neoplasms; Digital anal rectal examination; Early detection of cancer; HIV; Homosexuality; Male.

Fig. 1

Agreement and accuracy for lay anal examinations compared with clinician examinations in Chicago, Illinois and Houston, Texas, USA 2020–2022. Abbreviations: PPV, positive predictive value; NPV, negative predictive value.

Fig. 2

Concordance by lesion size between lay and clinician anal examinations stratified by anatomic site in Chicago, Illinois and Houston, Texas, USA 2020–2022. p value is derived from the Cochrane–Armitage test for trend. Size and number of lesions; 1 mm (n = 19), 2 mm (n = 84), 3 mm (n = 63), 4 mm (n = 31), 5 mm (n = 22), 6 mm (n = 13), 7 mm (n = 5), 8 mm (n = 6), 9 mm (n = 1), 10 mm (n = 1).