The benefits are clear in the study. WHY they exist is an unknown.

While I personally believe that even though the cervix and oropharynx are very different bits of anatomy, that this virus in each one has the same mechanism of invasion and cell domination/immortalization. Logic would dictate that the vaccines properties which interfere with the virus would be similar. But of course as always we lack a clinical model establishing proof.

The science to date, has convinced the OCF science board that fighting for boys vaccination was justified and worthwhile in oral cancers (not just genital warts), even though there was no hard clinical trial to justify it. As David has pointed out, this was accomplished by cooperating with a broad coalition of other stake holders like the HPV/Anal Cancer Foundation in arguments at the CDC. This was a big study, but conclusions about protection in head and neck recurrence is a more ambiguous issue that protection from the virus itself in a sexually/virus naive boy or girl.