Because heavy smoking and drinking do not further increase risk of head and neck cancer in people with human papillomavirus 16 (HPV 16) infection, it is probable that alcohol and tobacco cause these cancers through a different mechanism than HPV infection and that two distinct prevention and treatment strategies may be needed, according to an article in the December issue of the Journal of the National Cancer Institute.

While the Centers for Disease Control and Prevention recommends that girls and young women receive the HPV vaccine to prevent cervical cancer -- HPV16 causes about half of all cervical cancer cases -- boys and men cannot get the vaccine. An estimated 20 million Americans are currently infected with genital HPV and 50 to 75 percent of sexually active men and women are infected with HPV at some point in their lives, according to the National Institutes of Health.

"Our current HPV vaccine recommendations should change," Karl Kelsey, MD, study senior author said. "Head and neck cancers, regardless of their cause, are predominantly male diseases. If boys and men received the HPV vaccine, a lot of these cancers could be prevented."

Kelsey and his team tested the hypothesis of multiplicative risk. If HPV infection increases the risk of head and neck cancer, and alcohol and tobacco use also increases the risk, would a combination increase that risk exponentially?

To find out, the team studied 485 head and neck cancer patients who were diagnosed at nine Boston-area hospitals between December 1999 and December 2003. The team also studied 549 cancer-free comparison subjects who were closely matched with the study group based on age, sex and town of residence.

All subjects were asked about lifetime smoking and alcohol consumption and gave a blood sample that was screened for HPV16 antibodies, a sign of exposure. The team then conducted a statistical analysis to estimate the effects of different risk factors.

The found that smoking and drinking did not add to the risk of head and neck cancer for subjects exposed to HPV16. The strongest risk factors, by tumor site, were smoking for cancer of the larynx, alcohol with mouth cancer, and HPV infection with throat cancer.

"We have a profound bit of evidence that HPV16-associated head and neck cancer is a very different disease," Kelsey said. "Under a microscope, it looks like the same cancer you get from smoking and drinking. But how you get this form of the disease -- and how you would prevent and treat it -- is quite different."

"There is a huge prevention message here, which is that we could protect a lot of people from cancer if men and boys could get the HPV vaccine," Kelsey said. "We should start testing this vaccine on men."