A sexually transmitted virus that causes cervical cancer has been linked to cancers of the tonsil and tongue - diseases that have been on the rise in men for the past 30 years, according to a study by a Colorado Springs doctor and researcher.

Among Colorado men, such throat cancers have become 37 percent more common since 1980, compared with a national increase of 11 percent.

"Nobody knows that this is going on, and it's important to understand the risk," said Joel Ernster, a professor at the University of Colorado Denver School of Medicine and principal author of the study, which appeared in the journal Laryngoscope.

The trends point to oral sex as a likely mode of transmission and have prompted some to call for boys to be vaccinated against the human papilloma virus, Ernster said.

Girls can already receive a vaccine to prevent cervical cancer.

"Based on what they know right now, why the hell aren't they giving it to boys?" asked Jon Helander, 56, a patient of Ernster's in Colorado Springs.

Helander went through radiation and chemotherapy to fight a virus-related tongue cancer earlier this year and said he's frustrated that his son, 21, can't be vaccinated against the virus, as his daughter, 23, has been.

While the rate of tonsil and tongue cancer is lower in Colorado than nationally - about 3.47 cases per 100,000 people versus 4.81 - it is increasing more quickly, Ernster and his colleagues reported.

In Colorado, cases jumped from 2.54 per 100,000 to 3.47 in the past two decades, Ernster reported. Given the state's population growth, he said, that's an increase from about 50 cases per year in the 1980s to more than 100 today.

The researchers also found a steady increase since 1980 in the percentage of throat cancers in Colorado men testing positive for the human papilloma virus, from 33 percent in the 1980s to more than 80 percent today.

Sexual history possible factor

Ernster said he was trying to understand the shift he was seeing among throat cancer patients away from older, longtime smokers and drinkers to 45- to 55-year-old men married for 15 to 20 years.

"But if you ask what they did before that, they were promiscuous, had a lot of different encounters, and oral sex was part of their lives," Ernster said.

Helander, whose cancer tested positive for the human papilloma virus, said his history fits the pattern.

"Let's see - 20, 30 years takes me back to my years in the military," Ernster said. "So, yes, I know where it came from."

After Helander's cancer came back positive for the virus, he said, his ex-wife was tested. She was not infected.

Aimee Kreimer, an National Institutes of Health epidemiologist who has published research linking human papilloma virus to some throat cancers, said a variety of historic and social factors could explain Colorado's fast rate of increase among men.

Cancers related to the human papilloma virus have a long latency, she said, showing up 20 or more years after infection.

The sexual revolution of the '60s has certainly also contributed to the rise of viral-associated oral cancers, Kreimer said.

It's not clear why women aren't getting more of the cancers, she said.

Kreimer and Ernster said they worried that people are still underestimating the risks of oral sex, but both also said the human papilloma virus vaccine eventually could cut cancer rates.

Gardasil, manufactured by Merck & Co., can prevent HPV infection in girls, preventing cervical cancer.

"We're optimistic it will protect from infection at other anatomical sites too," Kreimer said.

Merck spokeswoman Jennifer Allen said the company does not yet have plans to test the vaccine's ability to prevent oral cancers in boys or men.

"It's all still new," Allen said.

"Who cares?" Helander said. "Gender's not going to make a difference. Just give it to my son."