Oral sex the culprit in rising numbers of throat cancers

Aug 28 2007

According to the latest figures on head and neck cancer, even though the rates for such cancers have dropped in recent years, throat cancer rates in the United States have not dropped.

Researchers from the Houston M.D. Anderson Cancer Center found in a recent analysis of head and neck cancer rates in the U.S. that the incidence of throat cancer could be on the rise.

They suggest the rise in oropharyngeal cancers, cancers of the tonsil and base of tongue, may be linked to oral sex and the sexually transmitted infection human papilloma virus (HPV).

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

The researchers say the findings serve to highlight the importance of research aimed at establishing if the newly available HPV vaccine is effective in males.

Researcher Dr. Erich Sturgis says the vaccine has been shown to be almost 100% effective for preventing cervical infection and its role in preventing oral cancer is worthy of investigation.

According to the American Cancer Society alcohol and tobacco are by far the biggest risk factors for head and neck cancers and 90% of patients with such cancers either smoke or chew tobacco or have done so in the past; up to 80% of oral cancer patients are also heavy drinkers.

The new analysis by Dr. Sturgis and co-author Dr. Paul M. Cinciripini, showed that the decline in smoking has led to a decline in most head and neck cancers over the past two decades with the exception of throat cancer.

Throat cancer is 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 are rare cancers and account for just 10,000 of the 45,000 head and neck malignancies diagnosed each year in the U.S. but tongue cancer rates among young adults have increased and the researchers believe this is due to to HPV infection being spread through oral sex.

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

The researchers say the current policy of vaccinating only females against HPV, could result in a missed opportunity to prevent throat cancers.

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

The vaccine Gardasil is recommended by the U.S. Centers for Disease Control and Prevention for 11- to 12- year-old girls, and for women up to age 26 who have not received it, which equates to 30 million women and girls; cervical cancer kills as many as 300,000 women worldwide each year.

Research is currently underway to determine if the vaccine protects boys against genital HPV infection.

U.S. health officials estimate that more than a quarter of girls and women aged 14 to 59 are infected with HPV.

The research is published in the current issue of the journal Cancer.