Routine Screening of Anal Cytology in Persons With Human Immunodeficiency Virus and the Impact on Invasive Anal Cancer: A Prospective Cohort Study

Background. The efficacy of screening programs to prevent anal cancer in persons with human immunodeficiency virus 1 (HIV-1) is unclear. Methods. To examine the impact of a screening program to detect anal cancer precursors on the incidence of cases of invasive anal squamous-cell carcinoma (IASCC) in persons with HIV-1, we performed a single-center, retrospective analysis of a prospective cohort of outpatients with HIV-1 attending a reference HIV unit from January 2005 onward. All participants were invited to participate in a continued structured screening program for anal cancer prevention. We estimated the incidence of IASCC and performed a comparative analysis between subjects enrolled in the screening program (screening group) and those who declined to participate (nonscreening group). To reduce any selection bias, a propensity score analysis was applied. Results. We included 3111 persons with HIV-1 (1596 men-who-have-sex-with-men [MSM], 888 men-who-have-sex-with-women [MSW], 627 women; mean age, 41 years), with a median follow-up of 4.7 years (14 595 patient-years of follow-up); 1691 (54%) participated in the screening program. Ten patients were diagnosed with IASCC: 2 (MSM) in the screening group and 8 (4 MSM, 2 MSW, and 2 women) in the nonscreening group. The incidence rates of IASCC were 21.9 (95% confidence interval [CI], 2.7-70.3) and 107.0 (95% CI, 46.2-202.0) per 100 000 person-years, respectively. After a propensity score adjustment, the difference was significant in favor of the screening group (hazard ratio, 0.17; 95% CI, .03-.86). Conclusions. The number of cases of IASCC was significantly lower in persons with HIV engaged in an anal cytology screening program. These results should be validated in a randomized clinical trial.