Anal self-examinations may help people identify pre-cancerous lesions and tumours

Anal self-examination has the potential to identify lesions that might be cancerous and should be promoted as a community-led tool to raise awareness of the need for anal cancer screening, the investigators of a prospective study in sexual minority men and transgender women report.

Anal cancer caused by human papillomavirus is far more common in gay and bisexual men than the rest of the population, especially in people living with HIV. Screening and treatment of precancerous anal lesions reduces the risk of anal cancer, while early treatment of anal cancer when lesions are small results in the best treatment response and less invasive treatment.

But screening for anal cancer does not take place in all health facilities due to lack of awareness and capacity. To investigate whether people at higher risk of anal cancer could successfully use self-examination techniques and to assess their acceptability, Dr Alan Nyitray, an epidemiologist specialising in anal cancer at Medical College of Wisconsin, carried out a study with colleagues in Chicago and Houston.

The Prevent Anal Cancer Palpation study enrolled 714 gay and bisexual men and transgender women in Houston and Chicago between 2020 and 2022 through social media, friends and in-clinic advertising. The study excluded people who already been diagnosed with haemorrhoids, anal warts or anal squamous cell carcinoma.

Study participants received approximately 15 minutes of training from a staff member at a participating clinic in how to carry out the self-examination. Participants were instructed to feel the entire perianal region with a finger and the anal canal to the depth of the second joint on the index finger, to check for any abnormalities. Couples participating in the study received training in how to carry out the examination on each other. Individuals who were self-examining were instructed to use a mirror or take a selfie to help locate abnormalities. The examinations typically lasted around four minutes and participants were paid $50 for taking part in the study.

The study participants had a median age of 40 years, 98% were male at birth, 1.5% were transgender women and 1.3% transgender men. Thirty-eight percent were living with HIV. Just under half (47%) were White, non-Hispanic, 23% were Black, non-Hispanic, 23% were Hispanic and 4% were Asian, non-Hispanic.

Most participants (92%) carried out self-examination; 8% received an examination from a companion. A non-clinician trained most participants (88%).

Participants underwent a clinician examination to check for abnormalities, so that the degree of concordance between lay examination and clinician examination could be assessed. Healthcare providers noted at least one abnormality in 34% of participants, most commonly haemorrhoids (46%) or skin folds, tags or flaps (47%).

The sensitivity of self or companion examination – the ability of participants to identify a true abnormality – was 59%. The specificity of self or companion examination – the ability of participants to know that there were no abnormalities – was 80%. There was little difference in accuracy between self and companion examination, type of lesion, site of lesion, self-reported dexterity or waist size.

Concordance between provider examination and self-examination was high (0.73) and greater if a clinician conducted the training (0.85 vs 0.72 for non-clinician training). Concordance increased with lesion size. Participants over 55 were less likely to be concordant with healthcare providers than participants aged 25-34. Black, non-Hispanic participants had a higher rate of concordance with healthcare providers than White non-Hispanic participants.

Ninety percent of participants described the self-examination process as easy or very easy, 9% as difficult or very difficult. Participants were highly likely to agree that they would repeat anal self-examination in the future (97%) and 93% said they would see a doctor if they were aware of a persistent anal abnormality in the future. Sixty-five percent preferred a future exam to be carried out by a doctor but one-third said that they would prefer to self-examine.

The median size of the lesions detected in this study was 3mm in diameter. Stage 1 tumours, the earliest form of anal cancer measure less than 20mm in diameter. The study investigators say that given the excellent treatment prognosis for anal cancers of less than 10mm in diameter, self-examination is likely to reduce anal cancer mortality and morbidity.

However, the study investigators also show that self-examination should not be relied on as a substitute for provider examination, as 13% of lesions were missed by self-examination and 13% of participants identified features in the perianal region or anal canal that turned out not to be lesions, potentially causing unnecessary anxiety.

The investigators recommend that healthcare providers should carry out a baseline examination with all male and transgender sexual minority patients and encourage regular self-examination so that problems can brought to the attention of healthcare providers early. They add that anal self-examination could prove a valuable community-led tool for raising awareness of the need for screening for anal cancer.