HPV Linked to Spike in Cancers of the Mouth

A decade ago, most of Dr. Brian Nussenbaum's oral cancer patients were men over age 60 who drank heavily and used tobacco. Now, the gender ratio is about even and most are ages 45-55, said Nussenbaum, an ear, nose, and throat doctor at Washington University. He estimated that 70 percent of the tumors he sees on the back of patients' tongues and tonsils are caused by human papillomavirus (HPV) type 16.

The National Cancer Institute recently determined the rate of HPV-related oral cancer has risen steadily since 1973. Experts suspect many cases stem from oral sex, from HPV infections that are dormant for years or decades before causing cancer.

"We know that 98 percent of cervical cancer is caused by HPV, and mostly HPV-16," Nussenbaum said. "But no one talks about how you can also get mouth cancer from it."

People with serologic evidence of HPV-16 infection are 32 times more likely to develop oropharyngeal cancer, according to a 2007 Johns Hopkins Kimmel Cancer Center study. Those who had more than six oral sex partners in their lifetime were 8.6 times more likely to develop HPV-positive oral cancer.

Even for patients with stage three and four HPV-related oral cancer, the three-year survival rate is about 90 percent, said Nussenbaum. "Even under a microscope, the tumor looks different," he said. "The shape and size of the cells are different."

Most major treatment centers are now trying to determine the lowest chemotherapy and radiation doses that are possible without lowering the cure rate, said Dr. Mark Varvares, St. Louis University's otolaryngology chairperson. In the future, experts hope to screen patients and partners using blood and saliva tests, though the tests used in the 2007 study are not yet available for clinics.

In the meantime, experts agree that awareness of HPV-associated oral cancer and its prevention, practicing oral sex with a dental dam or a condom, remain best.

Back to other news for October 2008