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Canadian studies released last year concluded that the type of “oro-pharyngeal” cancers — those at the base of the tongue and tonsils — usually associated with the virus have been on the rise, but scientists couldn’t prove a link to HPV. Researchers at London’s Lawson Health Research Institute went a step further, genetically analyzing tumour samples over time to detect changes in the actual presence of the infection.

They found that the number of patients with tonsil cancer, closely linked to human papillomavirus, more than doubled between the mid-1990s and late 2000s, with HPV present in almost three times as many of the most recent cancers.

The risk of contracting a virus-related throat cancer rises with the number of sexual partners, but anyone who has oral sex is at risk, noted Dr. David Palma, a radiation oncologist and co-author of the research.

“Many of the patients we are seeing have only had a few partners,” he said. “You don’t have to be promiscuous to get this cancer.”

The numbers are not huge in relative terms. The rate of oro-pharyngeal cancers rose to 2.6 per 100,000 in 2009, according to a study published last year by the Canadian Partnership Against Cancer.

That would mean about 860 new cases, compared with more than 22,000 new cases each of lung and breast cancer the same year. The throat numbers are expected to keep rising, though, and surpass those of cervical cancer by 2020, said Dr. Palma.

Patients with HPV-related throat tumours stand a good chance of being cured, but can suffer severe treatment side effects, from hearing loss to trouble swallowing and prolonged use of a feeding tube, he noted.