Anal Cancer Risk Among People With HIV Infection in the United States

Abstract

Purpose People with HIV infection have an elevated risk of anal cancer. However, recent calendar trends are incompletely described, and which population subgroups might benefit from cancer screening is unknown. Methods We used linked data from HIV and cancer registries in nine US areas (1996 to 2012). We calculated standardized incidence ratios to compare anal cancer incidence in people with HIV infection with the general population, used Poisson regression to evaluate anal cancer incidence among subgroups of people with HIV and to assess temporal trends, and estimated the cumulative incidence of anal cancer to measure absolute risk. Results Among 447,953 people with HIV infection, anal cancer incidence was much higher than in the general population (standardized incidence ratio, 19.1; 95% CI, 18.1 to 20.0). Anal cancer incidence was highest among men who have sex with men (MSM), increased with age, and was higher in people with AIDS than in those without AIDS (ie, HIV only; adjusted incidence rate ratio, 3.82; 95% CI, 3.27 to 4.46). Incidence among people with HIV increased steeply during 1996 to 2000 (annual percentage change, 32.8%; 95% CI, -1.0% to 78.2%), reached a plateau during 2001 to 2008, and declined during 2008 to 2012 (annual percentage change, -7.2%; 95% CI, -14.4% to 0.6%). Cumulative incidence after a 5-year period was high for MSM with HIV only age 45 to 59 or ≥ 60 years (0.32% to 0.33%) and MSM with AIDS age 30 to 44, 45 to 59, or ≥ 60 years (0.29% to 0.65%). Conclusion Anal cancer incidence is markedly elevated among people with HIV infection, especially in MSM, older individuals, and people with AIDS. Recent declines may reflect delayed benefits of HIV treatment. Groups with high cumulative incidence of anal cancer may benefit from screening.

Fig 1.

Trend in anal cancer incidence among people with HIV infection and the general population in the United States, 1996 to 2012. Dots indicate the observed incidence of anal cancer among people with HIV in the study population as a function of calendar year. The solid line is the model fitted by Joinpoint, with changes in slope for the incidence trend indicated in 2000 and 2008. The dashed line is the expected incidence in the general population standardized to reflect the demographic characteristics of the HIV population.

Fig 2.

Cumulative incidence of anal cancer in people with HIV infection in the United States. Cumulative incidence of anal cancer among (A) people with AIDS and (B) people with HIV only as a function of follow-up time. Each panel of (A) and (B) presents results for a different age-group as assessed at AIDS diagnosis (for people with AIDS) or HIV report (for people with HIV only). MSM, men who have sex with men.

Fig 3.

Cumulative incidence of anal cancer in men who have sex with men (MSM) with HIV infection in the United States during 1996 to 2000 and 2009 to 2012. Cumulative incidence of anal cancer among (A) MSM with AIDS and (B) MSM with HIV only as a function of follow-up time. The solid line corresponds to MSM with HIV reported or an AIDS diagnosis during the 1996 to 2000 calendar period, and the dashed line corresponds to HIV reported or an AIDS diagnosis during 2009 to 2012.

Fig A1.

Trend in incidence rate of anal cancer among people with HIV infection, 1996 to 2012. Dots indicate the observed incidence of anal cancer among people with HIV in the study population as a function of calendar year.