Adults With HIV at Increased Risk for Anal Carcinoma After Anogenital Warts

By Lisa Rapaport

January 25, 2021

(Reuters Health) - Adults living with HIV who have a history of anogenital warts may be at increased risk for developing anal carcinoma, a recent study suggests.

Researchers examined data on 6,515 adults living with HIV who received care at one of 14 HIV clinics in Washington, D.C., from January 1, 2011, to March 31, 2017. After a minimum follow-up period of 18 months, a total of 383 people (5.9%) were diagnosed with anogenital warts.

Individuals with this diagnosis were significantly more likely than those without it to develop anal carcinoma during the follow-up period (adjusted odds ratio 12.79), according to the results in JAMA Dermatology.

"Anogenital warts are a risk factor for anal cancer because both warts and most anal cancers are caused by HPV infection," said lead study author Dr. Justin Arnold of the George Washington University School of Medicine and Health Sciences in Washington, D. C.

"Therefore, a history of anogenital warts serves as a marker for previous HPV infection," Dr. Arnold said by email. "Additionally, individuals living with HIV have a higher risk for cancers because of their HIV-associated immunosuppression."

While the HPV vaccine can dramatically reduce the risk for developing anogenital warts and anal cancer, uptake of the HPV vaccine in the U.S. has been less than ideal, Dr. Arnold added.

"I have encountered many parents who adamantly refuse the vaccine for their children because they believe the vaccine will make their child more sexually promiscuous, or that the vaccine is only for teens who are already sexually active," Dr. Arnold said. "Additionally, for the HPV vaccine to be most effective, it should ideally be administered before one is sexually active."

In the study, 17 of 383 (4.4%) patients diagnosed with anogenital warts developed anal carcinoma, compared with 17 of 6,132 (0.03%) of patients without any history of anogenital warts.

Surveillance bias is one potential limitation of the study because patients weren't systematically screened for anogenital warts or anal carcinoma, the study team notes. It's possible that those with a history of anogenital warts were more likely to be screened for anal carcinoma. Researchers also lacked data on HPV vaccination status, or whether any vaccinated individuals were inoculated prior to becoming sexually active.

While all people living with HIV are at increased risk for anal cancer, clinicians should pay particular attention to certain subgroups that are at the highest risk, said Dr. Joel Palefsky, a professor of medicine at the University of California, San Francisco who wasn't involved in the study.

The highest risk groups include men who have sex with men, particularly those with lower CD4 nadir and those with a history of anogenital warts, Dr. Palefsky said by email.

There are no guidelines from the U.S. Centers for Disease Control and Prevention or the U.S. Preventive Services Task Force for screening for anal cancer in any of these high-risk groups, Palefsky noted. However, several medical societies do recommend screening with anal cytology followed by high resolution anoscopy if these are available.

"In the absence of their availability, my personal opinion is that all persons living with HIV should undergo a regular digital anorectal examination to feel for hard lumps that may indicate the presence of an anal cancer," Dr. Palefsky said.

SOURCE: JAMA Dermatology, online January 13, 2021.