A recent study reported in Clinical Infectious Diseases found that anal warts in men who have sex with men (MSM), notably those living with HIV, often contain cancerous and precancerous cells and should be surgically removed.

Anal warts are typically caused by two strains of the human papillomavirus (HPV): HPV types 6 and 11. Because these strains are thought to be low risk for cancer, most people either forgo treatment or opt for minimally invasive procedures such as freezing or burning. But considering the finding that almost half the anal warts collected from MSMs (47 percent) were studded with cancerous or precancerous cells, caused by more sinister HPV types, the study authors claim invasive removal of anal warts is necessary.

Joel Palefsky, MD, an HPV expert at the University of California at San Francisco, cautions that more research is needed to show whether surgically removing those warts will reduce cancer rates. Until then, he suggests people have their anal warts biopsied—and consider more aggressive treatments if the warts prove precancerous or cancerous or if they return.