FRIDAY, July 19 (HealthDay News) -- Young women who are vaccinated against the human papillomavirus (HPV) not only protect themselves from cervical cancer, but from throat cancer as well, a new study suggests.
Many of the increasing number of throat cancers, seen mostly in developed countries, are caused by HPV infection and the HPV vaccine might prevent many of these cancers, the researchers say.
"We found the women who had the HPV vaccine had much less infection than the women who hadn't," said lead researcher Dr. Rolando Herrero, at the International Agency for Research on Cancer in Lyon, France.
"In fact, there was a 90 percent reduction in the prevalence of HPV infection in the women who received the vaccine compared to the women who had not," he said.
HPV infection is strongly associated with cancer of the oral cavity, Herrero noted. "We think that it is possible that the prevention of the infection will also lead to the prevention of these cancers," he explained.
The HPV vaccine has enormous benefit, said Herrero, "because of the cervical cancer prevention and the anal cancer prevention, and it can even prevent infections in their sexual partners."
Herrero said boys, too, should be vaccinated to protect them from oral cancers. Oral cancer is much more prevalent among men than in women, he pointed out.
A 2011 study in the Journal of Clinical Oncology showed that in the United States, HPV-positive oral cancers increased from 16 percent of all oral cancers in the 1980s to 70 percent in the early 2000s.
And according to the Oral Cancer Foundation, nearly 42,000 Americans will be diagnosed with oral and throat cancer in 2013, and more than 8,000 people will die from these conditions.
HPV-linked throat cancer recently came to the public's attention when the British newspaper The Guardian reported that actor Michael Douglas' recent bout with the disease might have been caused by oral sex.
For the new study, Herrero's team randomly assigned more than 7,400 women aged 18 to 25 to either receive the HPV vaccine or a vaccine against hepatitis A, as a comparison.
Women in the HPV vaccine group were given Cervarix, one of two vaccines available for HPV prevention. (The other is Gardasil.)
Four years later, the researchers found the HPV vaccine was 93 percent effective in preventing throat cancer. Among women who received the HPV vaccine, only one patient showed an oral HPV infection, compared with 15 in the hepatitis A vaccine group, the researchers found.
The HPV vaccine costs $130 a dose and because three shots are required, the total cost is about $390, according to the U.S. Centers for Disease Control and Prevention. There are government programs that can help offset these costs for some patients, the agency noted.
Because HPV is a sexually transmitted infection, the vaccine is most effective when given before someone is sexually active. Eighty percent of people will test positive for HPV infection within five years of becoming sexually active, said Dr. Marc Siegel, an associate professor of medicine at NYU Langone Medical Center, in New York City.
That's why the CDC recommends the vaccine for adolescent girls and boys starting at age 11.
The new report was published in the July issue of the online journal PLoS One.
"The study is really preliminary information," said Dr. Elizabeth Poynor, a gynecologic oncologist and pelvic surgeon at Lenox Hill Hospital, in New York City. "It will provide a basis to begin to study how the vaccine will help to protect against throat cancer," she noted.
"It's going to take a while to study those who have been vaccinated to determine that they are protected against throat cancer. This is just the beginning," she said.
"It also really highlights that we need to vaccinate young boys," Poynor added.
For more about HPV and cancer, visit the U.S. National Cancer Institute .