The basics are fascinating and more than a little alarming. For decades, head and neck cancers were found mostly among older men—and not just any men, but those who were serious drinkers and smokers. In the years of the observations, of course, drinking and smoking were, for the most part, a man’s redoubt. Women hadn’t come a long way, baby, to become addicted to tobacco until relatively recently. And it seemed that alcohol and tobacco worked together in toxic synergy to produce the malignancy.

But a decade or two ago, the groups at risk for the disease and, as important, the anatomic site of the cancer changed drastically. No longer were drinkers and smokers the ones with the disease but rather abstemious folks—and younger ones, at that—who never had spent time detoxing or trying to kick the habit. Furthermore, the tumor arose from tonsils and the base of the tongue, once rare sites of cancer development, not the oropharynx, as was seen in the old-school version. Next came important work associating HPV with most of these new tongue and tonsil tumors. Articles going back to the 1990s found the first hint, then important subsequent work brought the connection front and center into wide acceptance.

Given the known association between cervical cancer and HPV, and the knowledge that HPV moved from man to woman via vaginal intercourse, as well as the increasing number of cases HPV-triggered rectal and anal cancers among gay men, the notion that HPV-related oral cancer is transmitted by oral sex has a certain surface logic.

Yet there are several problems with the assumption.