Their study involved 323 patients with stage III or IV oropharyngeal cancer (cancers of the upper throat) who were part of a Radiation Therapy Oncology Group clinical trial. Of these patients, 206 had HPV-positive tumors and 117 had HPV-negative tumors.
"Our findings show that HPV status is as strong a predictor of outcome as cancer stage for patients with oropharyngeal cancers, even after considering other factors such as age and smoking history," said lead author Maura Gillison, M.D., Ph.D., a medical oncologist and head and neck cancer specialist at the Ohio State University Comprehensive Cancer Center-James Cancer Hospital and Solove Research Institute. "We're still not entirely sure why this is, but these data provide further evidence that HPV-positive oropharyngeal cancer is a distinct disease entity."
Previous smaller studies by Dr. Gillison and others have suggested that oropharyngeal cancer patients with HPV-positive tumors fare better than their HPV-negative counterparts. But patients with HPV-positive oropharyngeal cancer tend to be younger and have smaller tumors at diagnosis, and they are less likely to smoke than HPV-negative patients. This is the first study large enough to consider HPV together with these other factors in patients who received the same therapy in a large clinical trial, according to the researchers.
Dr. Gillison and her colleagues compared the patients for overall survival and progression-free survival, the time it took for cancer to again progress.
After a median follow-up of 4.5 years and controlling for possible confounding factors such as therapy and smoking status, 88% of the HPV-positive patients were still alive after two years compared with 66% of HPV-negative patients. Progression-free survival for HPV-positive patients was 72% and 50% for HPV-negative patients after two years. The incidence of second primary cancers among HPV-positive patients was less than half that of HPV-negative patients: 4% versus 11%.
The findings suggest that patients with HPV-positive tumors have less than half the chance of dying from their cancers in five years compared to those with HPV-negative tumors, the researchers concluded.
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