Virus Linked To Throat Cancer Trend

GENERIC Cancer cells health CBS/AP

Unlike most head and neck cancers, throat cancer rates in the United States have not dropped in recent years, and infection with the sexually transmitted infection human papilloma virus (HPV) may be the cause.

HPV is a virus that causes genital warts and most cervical cancers, but its transmission through oral sex has only recently been identified as a potential cause of throat cancer.

In a newly published analysis of head and neck cancer rates in the U.S., researchers from Houstonb's M.D. Anderson Cancer Center found the incidence of throat cancer to be stagnant and even rising in some populations, defying a downward trend in other head and neck cancers linked more closely with smoking.

The findings underscore the importance of research aimed at determining if the newly available HPV vaccine is effective in males, researcher Erich Sturgis, M.D., MPH, tells WebMD.

"The vaccine has been shown to be almost 100% effective for preventing cervical infection," he says. "We would encourage the medical community and [vaccine] industry to study its role in preventing this oral cancer."

Tobacco use and drinking alcohol are by far the biggest risk factors for head and neck cancers. About 90% of patients with these malignancies either smoke or chew tobacco or have done so in the past, and up to 80% of oral cancer patients also drink a lot of alcohol, according to the American Cancer Society.

In their newly published analysis of head and neck cancer trends in the U.S., Sturgis and co-author Paul M. Cinciripini, M.D., showed that the decline in smoking has led to a decline in most head and neck cancers over the past two decades.

"These decreasing incidence rates trail by 10 to 15 years the declines in smoking prevalence, which began in the 1970s," they wrote in the Oct. 1 issue of the journal Cancer.

The main exception to this trend has been throat cancer, more specifically defined as cancer of the oropharynx, which includes the tonsils, base of the tongue and soft palate, and side and back of the throat.

These cancers are rare, accounting for just 10,000 of the roughly 45,000 head and neck malignancies diagnosed each year in the U.S. But their incidence has remained steady, overall, Sturgis and Cinciripini write, and tongue cancer rates among young adults have increased.

They conclude that this is likely due to HPV infection, spread through oral sex.

Sturgis tells WebMD that over the last five years, 35% of the throat cancer patients treated at M.D. Anderson Cancer Center had no history of smoking and that close to 90% of patients who had never smoked showed evidence of oral infection with HPV.

In the conclusion of their analysis, the researchers write that vaccinating only females against HPV, which is currently the policy in the U.S., could result in a missed opportunity to prevent throat cancers.

The HPV vaccine is being offered to males in Australia, Mexico, and some other countries, but there is, as yet, no clinical proof that it works to prevent HPV infection in men, says Debbie Saslow, PhD, of the American Cancer Society.

In the U.S. the vaccine, marketed as Gardasil by Merck & Co., is recommended for 11- to 12- year-old girls, and for women up to age 26 who have not received it.

Studies are under way to determine if the vaccine protects boys against genital HPV infection.

"The HPV vaccine is very effective protection against cervical cancer, and there is a good chance that it will reduce the incidence of other types of HPV-promoted cancers as well," Saslow tells WebMD. "But we have no data to confirm that, and we won't have any in the near future."


By Salynn Boyles
Reviewed by Louise Chang
© 2007 WebMD, Inc. All rights reserved

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