Dr. Robert Haddad, chief of the center for head and neck oncology at the Dana-Farber Cancer Institute in Boston, said his clinic is "packed with patients" in their 40s and 50s with oral cancer, but HPV-related oral cancer was unheard of 15 years ago.
"They never smoked, don't have heavy alcohol use, and often have young children," he told The Boston Globe. Often these cancers aren't diagnosed until they've progressed to surrounding lymph nodes making them harder to cure, he said.
About 14,000 throat cancers are diagnosed every year in the United States and most are related to HPV, Haddad said.
HPVs are a group of more than 150 related viruses. More than 40 of these viruses can be easily spread through direct skin-to-skin contact during vaginal, anal and oral sex, the Centers for Disease Control and Prevention said.
HPV infections are the most common sexually transmitted infections in the United States. More than half of sexually active people are infected with one or more HPV types at some point in their lives and at any point in time, 42.5 percent of women have genital HPV infections, but less than 7 percent of adults have oral HPV infections, the National Cancer Institute said.
Sexually transmitted HPVs fall into two categories. Low-risk HPVs do not cause cancer but can cause skin warts on or around the genitals or anus. For example, HPV types 6 and 11 cause 90 percent of all genital warts.
However, high-risk or oncogenic HPVs can cause cancer. At least a dozen high-risk HPV types have been identified. Two of these, HPV types 16 and 18, are responsible for the majority of HPV-caused cancers.
Most high-risk HPV infections occur without any symptoms, go away within one to two years and do not cause cancer.
Some HPV infections persist for many years, lead to more serious lesions and, if untreated, might progress to cancer.
Researchers said it could take 10-20 years from the time of an initial HPV infection until a tumor forms, but not all high-grade lesions lead to cancer.
The most reliable way to prevent infection with either a high-risk or a low-risk HPV is to avoid any skin-to-skin oral, anal or genital contact with another person. However, because of the lack of symptoms it is hard to know whether a partner who has been sexually active in the past is currently infected with HPV, the Cancer Institute said.
A 2006 study in the New England Journal of Medicine Research showed the correct and consistent use of condoms could reduce the transmission of HPVs between sexual partners, but areas not covered by a condom could be infected with the virus.
The U.S. Food and Drug Administration approved two HPV vaccines: Gardasil for the prevention of cervical, anal, vulvar and vaginal cancer, as well as precancerous lesions in these tissues and genital warts caused by HPV infection; and Cervarix for the prevention of cervical cancer and precancerous cervical lesions caused by HPV infection.
Both vaccines are highly effective in preventing infections with HPV types 16 and 18. Gardasil also prevents infection with HPV types 6 and 11, the Cancer Institute said.
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