Incidence of Anal Cancer and Related Risk Factors in HIV-Infected Patients Enrolled in the National Prospective Spanish Cohort CoRIS

BACKGROUND: People living with HIV have an increased risk of anal cancer. OBJECTIVE: To estimate anal cancer incidence and related risk factors in a national cohort of HIV-infected patients. DESIGN: Prospective multicenter cohort study. SETTINGS: Multicenter study including patients from the Spanish HIV Research Network. PATIENTS: We collected data from 16,274 HIV-infected treatment-naive adults recruited from January 2004 to November 2020. MAIN OUTCOMES MEASURES: The primary outcome measures of this study were the incidence and prevalence of anal carcinoma. The secondary outcome measures included the associations between baseline and time-dependent covariables and the primary end point. RESULTS: Twenty-six cases of anal cancer were diagnosed, 22 of which were incident cases resulting in a cumulative incidence of 22.29 of 100,000 person-years, which was stable during the study period. At the end of the study, 20 of the 43 centers had screening programs for high-grade anal dysplasia. Patients with anal cancer were males (26/26; 100% vs 13,833/16,248; 85.1%), were mostly men who have sex with men (23/26; 88.5% vs 10,017/16,248; 61.6%), had a median age of 43 years (interquartile range, 3551), were more frequently previously diagnosed with an AIDS-defining illness (9/26; 34.6% vs 2429/16,248; 15%), and had lower nadir CD4 cell counts (115 vs 303 uL). About a third (34.6%, 9/26) were younger than 35 years. In multivariable analysis, men who have sex with men and patients with previous AIDS-defining illness had an 8.3-fold (95% CI, 1.936.3) and 2.7-fold (95% CI, 1.16.6) increased HR for developing anal cancer, respectively. Patients with higher CD4 cell counts during the follow-up showed a 28% lower risk per each additional 100 CD4 cell/uL (95% CI, 41%22%). LIMITATIONS: Lack of information on some potential risk factors, screening, and treatment of high-grade anal dysplasia were not uniformly initiated across centers during the study period. CONCLUSIONS: Although the overall incidence in our study was low, there was a significant number of patients younger than 35 years with anal cancer. In addition to age, other factors, such as men who have sex with men and patients with severe immunosuppression (current or past), should be prioritized for anal cancer screening.