Human papillomavirus, or HPV, the leading cause of cervical cancer in women, appears to be a major cause of oral cancer in men, a new study reported.

The rise in cancers of the mouth and upper throat may be the result of an increase in oral sex and a decrease in smoking. HPV is now causing as many oral cancers as tobacco and alcohol.

The new study analyzed more than 30 years of National Cancer Institute data on oral cancers. Researchers looked at about 46,000 cases, dividing them into oral cancers caused by HPV and oral cancers not connected to the virus.

Their conclusion was that the incidence rates for HPV-related oral cancers rose steadily in men between 1973 and 2004, becoming about as common as those from tobacco and alcohol. Researchers also revealed that survival rates for the cancer are also increasing and that is because tumors caused by HPV respond better to chemotherapy and radiation, said co-author of the study Dr. Maura Gillison of Johns Hopkins University.

“If current trends continue, within the next 10 years there may be more oral cancers in the United States cause by HPV than tobacco or alcohol,” the study said.

In an effort to decrease the rates of cancer, Merck & Co. Inc., the manufacturer of Gardasil, the only vaccine against HPV is seeking to ask government permission to offer the shot to boys this year. Currently, the shot is targeted at girls and young women.

Annually, nearly 12,000 American women are diagnosed with cervical cancer. About 3,670 deaths were reported in the U.S. from cervical cancer in 2007, according to data from the American Cancer Society.

“We need to start having a discussion about those cancers other than cervical cancer that may be affected in a positive way by the vaccine,” Dr. Gillison said.

However, no data of how successful the vaccine would be in men are available yet. Therefore, government officials and the American Cancer Society cannot pronounce yet in this matter and say more study is needed.

The study was published in the Friday’s issue of the Journal of clinical Oncology.