Understanding who is at risk for infection with types of HPV that can cause anal cancer

What is it about?

Gay and bisexual men (and other men who have sex with men) are at significantly greater risk of developing anal cancer. A majority of these anal cancer cases are caused by human papillomavirus (HPV), a very common sexually transmitted infection (STI) with many different strains, some of which are known to cause cancer—like cervical cancer, which is the one most people have heard about. We wanted to find any patterns in who was more likely to test positive for HPV, focusing specifically on strains that we know are associated with greater risk for anal cancer. To do this, we took a deep dive into five years' worth of data on the identities, behaviors, and HIV/STI test results of a diverse sample of young adult men (mostly) who have sex with men. At the first visit, people who started the study already testing positive for at least one type of HPV were more likely to also test positive for herpes (HSV), compared to those who didn't have HPV. They also reported more sex partners in the previous month and were more likely to smoke cigarettes in the previous 6 months. We used this information on who tested positive at the first visit as our baseline, and then we looked at who was testing positive at the next two visits for a type of HPV that didn't already have. At the second visit, people who tested positive for a new type of HPV were more likely to have tested positive for herpes and to have tested positive for a different (not anal cancer-causing) type of HPV. At the third visit, people who tested positive for a new type of HPV were more likely to be HIV-positive, to have tested positive for herpes, or to have tested positive for a different anal cancer-causing type of HPV at the previous visit. They also reported more sex partners in the previous month, compared to those who didn't test positive for a new type of HPV at the third visit.

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Photo by charlesdeluvio on Unsplash

Photo by charlesdeluvio on Unsplash

Why is it important?

People who are living with HIV, who have tested positive for herpes or any type of HPV, and who have multiple sexual partners should be prioritized in efforts to improve rates of HPV vaccination. Especially given low rates of vaccination among gay and bisexual men (and cisgender men overall), healthcare providers should be vigilant about recommending vaccination to people who meet these criteria for increased risk of anal cancer-causing HPV. Unlike with cervical cancer screening, there aren't formal recommendations for routine anal cancer screening, but people who fall into these higher-risk categories may consider discussing screening options with their healthcare providers.

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