Treating abnormal anal cell changes early can reduce the risk of progression to anal cancer in people living with HIV, according to long-awaited results from the ANCHOR study. This suggests that screening to detect precancerous anal lesions should be part of routine care.

Anal cancer, like cervical cancer, is caused by human papillomavirus (HPV). Men who have sex with men are especially prone to anal cancer, but women get it too. People with HIV have more types of cancer-causing HPV and experience more rapid progression from low-grade abnormal cell changes to precancerous lesions (high-grade squamous intraepithelial lesions, or HSIL) to invasive cancer. While widespread screening has dramatically cut the risk of cervical cancer, anal cancer screening is currently not standard care for people with HIV.

In the ANCHOR study, 4,446 participants were screened for HSIL using anal Pap smears and anoscopy (examination of the anal canal with a scope). Those with precancerous lesions were randomly assigned to either receive immediate treatment or undergo active monitoring. The most common treatment was electrocautery, which uses an electric current to remove abnormal lesions. The trial was halted early after an interim analysis showed that early treatment offers a clear benefit: Removing HSIL significantly reduced the chances of progression to anal cancer.

“ANCHOR data show for the first time that, like cervical cancer, anal cancer can be prevented even in high-risk populations, such as people living with HIV, who often have HSIL that can be difficult to treat,” says Joel Palefsky, MD, of the University of California at San Francisco.

Advocate Jeff Taylor suggests the results may make it easier for HIV-positive people to get their insurance to cover anal cancer screening.