Traces of human herpesvirus 8 (HHV-8) have been found in almost all Kaposi’s sarcoma (KS) lesions. But which came first, the virus or the cancer? A University of California, San Francisco, study in the New England Journal of Medicine recently revealed that a man who is infected with both HIV and HHV-8 faces a 50 percent chance of developing KS within a decade. Plus, the odds of getting HHV-8 increase with the number of same-sex partners. Said the study’s lead author, Dr. Jeffrey Martin, “If you have HHV-8, you’re more likely to get KS, though we don’t know exactly how HHV-8 causes the KS.”

This study is the first to officially link KS to sex via HHV-8. Of the 800 men, whose first blood samples were taken in 1984, HHV-8 antibodies were found in more than a third of those who had unsafe, same-sex encounters within the previous five years; none were found in the 195 who didn’t. “This doesn’t mean that HHV-8 is only transmitted by homosexual sex,” said senior study author Dr. Dean Kedes. “But it suggests that in the [gay] population, the major mode of transmission is sexual.” Martin is eye-high in research to determine the specific type of sex that spreads HHV-8 in order to target future prevention efforts. “When you find a virus that’s responsible for a cancer, that’s an important opportunity for intervention,” he said.