Trends in the Incidence of HPV-Associated Anal Cancer by Risk Group, 1990-2019: A Population-Based Cohort Study in British Columbia, Canada.

BACKGROUND

Anal squamous cell carcinoma caused by human papillomavirus disproportionately affects people living with human immunodeficiency virus (HIV; PLWH), particularly gay, bisexual, and other men who have sex with men (GBM). New guidelines recommend screening and treatment of precancerous lesions. We aimed to estimate anal cancer incidence by HIV status, sex, and GBM status in British Columbia, Canada.

METHODS

Using administrative health databases, we assessed anal cancer stratified by HIV status, sex, and sexual orientation from 1990 to 2019. A phenotypic algorithm was used to classify GBM status. We evaluated the comparative incidence of anal cancer using Fine and Gray's competing risks subdistribution hazards model. Hazard ratios (HR) were estimated and adjusted for age, healthcare utilization, urbanicity, and Charlson comorbidity index.

RESULTS

Among 571 anal cancer diagnoses assessed, the incidence was highest among GBM with HIV [78.09 per 100,000 person-years (PY); 95% confidence interval (CI), 61.24-99.58], followed by heterosexual males with HIV (44.49 per 100,000 PY; 95% CI, 29.56-66.95) and females with HIV (12.05 per 100,000 PY; 95% CI, 4.52-32.11). GBM with HIV experience a 76-fold increased anal cancer risk compared with heterosexual men without HIV (adjusted HR 76.08; 95% CI, 55.14-104.97).

CONCLUSIONS

There is an unmet need in anal cancer prevention among PLWH. Screening strategies that are sensitive, specific, acceptable, and cost-effective are necessary.

IMPACT: This study provides the first population-based estimates of anal cancer incidence by HIV and GBM status in British Columbia, highlighting disparities and rising trends. These findings support prioritizing targeted screening programs and improving access to care.