Patients with head and neck cancer who have been non-smokers have much better survival rates after radiation therapy than those with a history of smoking.
The study by Allen M. Chen and colleagues in the UC Davis radiation oncology and otolaryngology departments is among the first of its kind to examine prognosis differences based on smoking history in patients with head and neck cancer who are treated with radiation therapy.
They found that patients with a history of smoking were more likely to die from their disease and more likely to experience a recurrence after radiation therapy than those without a smoking history.
Chen suspect one possible explanation for the difference in response to radiation is human papillomavirus (HPV), a sexually transmitted disease that has been highly associated with head and neck cancer in people who have never smoked.
"The most common theory is that these tumors express a characteristic viral antigen on the cell surface that makes the immune system recognize the cancers more readily, which may enhance the effects of radiation," he said.
"Another theory is that patients who have never smoked and who have HPV-related tumors have fewer mutations in key genes that are critical for radiation response," he added.
Chen compared 70 patients treated at the UC Davis Department of Radiation Oncology with newly diagnosed, non-metastatic squamous cell carcinoma of the mouth and throat who had a history of smoking with 70 patients with similar diagnoses who reported they had never smoked.
The study has been published online in American Journal of Clinical Oncology.