Clinical researchers at Princess Margaret Hospital (PMH) have confirmed that patients with oropharyngeal squamous cell cancer ("tonsil cancer") harbour a common type of human papilloma virus (HPV16), but also that such cancers are very sensitive to radiation. For some patients, this may mean successful treatment with radiation alone and avoiding the side effects of chemotherapy.
"This represents the power of personalized medicine. By using a relatively simple molecular test to evaluate the tumour, we can customize the treatment plan, produce an excellent outcome, and maintain the patient's quality of life," says principal investigator Dr. Fei-Fei Liu, PMH radiation oncologist, Head of the Division of Applied Molecular Oncology, Ontario Cancer Institute, and Dr. Mariano Elia Chair in Head & Neck Cancer Research, University Health Network.
The findings were published on November 2 in the Journal of Clinical Oncology (JCO 231670).
Dr. Liu's team discovered that patients whose tumours tested positive for HPV16 had a much better survival, compared to patients whose tumours did not harbour HPV16. This HPV effect was independent of treatment (radiation alone, or radiation plus chemotherapy), suggesting that some HPV16 patients could be treated with radiation only. As a result, PMH now routinely tests tonsil-area tumours for HPV16 -- one of the first cancer programs to do so.
The study's finding is important because this particular type of cancer is increasing - up more than 10% in the past 20 years. The jump is likely attributed to the spread of HPV16 through sexual activity, compared with a 20% decline in other similar head-and-neck cancers over the same period because fewer people are now smoking.