Link with virus that causes cervical cancer and head and neck cancers
In an article in the journal Science head and neck cancer specialist Wendell Yarbrough says that when he started practicing in 1994 his patients were typically in their 50s and 60s and smoked and drank heavily. Now, apparently the average age is far younger, late 20s or 30s, and many patients do not smoke.
In the US the national rate of head and neck cancers is declining, but at the same time the number of patients under the age of 50 is increasing. In fact, according to surveillance data from the National Cancer Institute (NCI), rates of oropharyngeal cancer in the 20 to 49 age group more than doubled from 1975 to 2005.
A search for the cause has suggested that the human papilloma virus, the same strains that cause 70% cervical cancer in the US, is to blame. In November, an epidemiological analysis from the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, linked up to 60% of oropharyngeal cancer cases from 1998 and 2003 to HPV.
Public health officials are now re-evaluating vaccine programmes and this year Merk s seeking to get its anti-HPV vaccine Gardasil, which was approved for women in 2006, approved for use in men.
At the moment no-one knows what the risk factors are and how behaviour may put someone at risk of head and neck cancer through HPV infection. Large epidemiological studies have been building up a picture of how HPV may be involved.
Risk factors for HPV-negative tumors included several decades of pack-a-day smoking, years of heavy drinking, and losing teeth--but not having more sex partners. In contrast, having more oral sex partners significantly increased the risk of developing HPV-positive cancer. Unexpectedly, a history of heavy marijuana usage also seemed to increase risk for HPV-negative tumors in these patients.
It appears that HPV-positive oral cancer isn't just a subset of oral cancer but a completely independent disease.
Now, further large epidemiological studies are needed to elaborate the risk factor profile.
