Anal carcinoma risk elevated in individuals with HIV and anogenital warts

Anal carcinoma risk was significantly higher among individuals with HIV and a history of anal or genital warts than among those with no history of these warts, according to a study.

“In the U.S., incidence of and mortality due to anal carcinoma are rising faster than for most other cancers,” Justin D. Arnold, MD, MMSc, of George Washington University School of Medicine and Health Sciences and Riverside Community Hospital at the University of California, Riverside, and colleagues wrote. “Identifying populations who have a higher risk of developing anal cancers is critical to target preventive interventions.”

In the longitudinal cohort study, Arnold and colleagues aimed to assess anal carcinoma risk in a cohort of 6,515 adults with HIV.

Participants were culled from 14 clinics in Washington, D.C., and followed for a minimum of 18 months. Data collection occurred between Jan. 1, 2011, and March 31, 2017.

Onset of warts in the anal or genital region served as the exposure of interest, while anal carcinoma as assessed by diagnostic codes and biopsy results served as the primary outcome measure.

Results showed that 5.9% of the overall cohort developed anogenital warts during the study period. Anal carcinoma developed in 4.4% of those with anogenital warts but only 0.3% of those who did not develop anogenital warts (P < .001).

Adjusted analysis results showed that the likelihood of developing anal carcinoma was 12.79 times higher in the anogenital warts group compared with those with no such history (P<.001).

Looking deeper into the findings, 88.2% of cases of anal cancer in the anogenital warts group and 82.4% of those cases in the non-warts group occurred in individuals with CD4 nadir levels less than 200 cells/µL. Overall, this CD4 level nadir yielded a 5.73-fold elevation in risk for anal cancer development independent of anogenital wart status (P < .001).

However, other factors that underwent analysis carried no such association, including smoking history. In addition, compared with men who have sex with men, neither intravenous drug use nor high-risk heterosexual contact were associated with anal carcinoma development.

“These findings suggest that adults living with HIV who have a history of anogenital warts have a substantially increased risk of developing anal carcinoma,” Arnold and colleagues wrote. “Clinicians should counsel individuals living with HIV who have anogenital warts on this risk.”