Anal Cancer Incidence Rates Among Men and Women With and Without HIV in South Africa.

Background: More than 7.5 million people in South Africa have HIV, but little is known about the association of HIV and anal cancer incidence. We examined anal cancer incidence in a large South African cohort of insured men and women.

Methods: We conducted a cohort study using reimbursement claims data from a South African medical insurance scheme (01/2011-07/2020) to assess anal cancer rates among people with and without HIV aged ≥18 years. We estimated adjusted hazard ratios (aHRs) for the association of HIV and incident anal cancer using flexible parametric survival models. Covariates included sex, age, calendar year, a history of genital warts and other sexually transmitted infections, and in women, cervical precancer.

Results: We included 1 068 915 people of whom 69 985 (7%) were living with HIV. Over 3 933 145 person-years, 122 anal cancers were diagnosed (crude rate: 3.1/100 000 person-years; 95% confidence intervals [CI] 2.6-3.7). People with HIV had a 4-fold higher anal cancer risk than people without HIV (aHR 4.43; 95% CI 2.44-8.04). While anal cancer rates were similar among men and women, older age (≥65 vs 45-54 years; aHR 5.01; 95% CI: 2.94-8.53), a history of genital warts (aHR 7.56; 95% CI: 2.28-25.07), and among women, a prior cervical precancer diagnosis (aHR 5.70; 95% CI 1.75-18.58) were associated with a higher anal cancer risk.

Conclusions: In South Africa, men and women with HIV, older individuals, people with a history of genital warts, and women with a prior cervical precancer diagnosis might benefit from prioritized access to anal cancer screening.