Although we are nowhere near proving a direct causation, studies have found HPV DNA in anywhere from 20-85% of tumors studied. (Types 16, 18 and 33 most commonly) However, some studies have found HPV DNA in normal breast tissue as well. So is HPV a cancer-causing agent in the breast or just a bystander? It’s too soon to say. Lots more work is needed on this one, folks.
The data are at odds with known risk factors for breast cancer, such as never having been pregnant. And if there is a link, one should see that breast cancer risk is increased with number of sexual partners, which as far as I know, is not the case.
So be careful before making the leap between hypothesis and recommending HPV vaccination for breast cancer protection. It’s way, way to soon…
