Head and Neck Cancer Survival Rates Better for ‘Never-Smokers’

Individuals who have never lit up a cigarette appear to enjoy a hedge against the mortality rates associated with head and neck cancer following radiation therapy. This phenomenon is reflected in a study conducted at the University of California, Davis (UC Davis) Cancer Center that demonstrates lower recurrence rates of the disease and fewer complications after radiation treatment experienced by patients who had never smoked.

Though the findings are good news for “never-smokers,” the researchers do not entirely understand what is behind the encouraging statistics. “These tumors just melt after a few doses of radiation,” notes study leader, Allen M. Chen, MD, director, residency and fellowship training program at UC Davis Cancer Center. “If we could understand why, there would be important implications for new drugs and treatments.”

Chen’s study compared 70 patients who had smoked with 70 patients who had never smoked. Cancer recurred in 26 patients who had a history of smoking, compared to only 14 never-smokers. Three years after treatment, 82% of never smokers were cancer-free in contrast to 65% of those who had smoked. In addition, complications associated with treatment were lower among never-smokers.

The reason never-smokers responded more favorably than smokers to radiation treatment may have a connection to the presence of the human papilloma virus (HPV), Chen theorizes. Chen explains a viral antigen expressed on the surface of an HPV cell may allow the immune system to more easily recognize cancers and, in turn, heighten the therapeutic effects of radiation used against the cancer. “Another theory, he says, “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.”

An increasing incidence of oropharyngeal squamous cell cancer, particularly among white males younger than age 50, has been noted in the last 10 years, according to an article published in the August 2010 issue of The Lancet. The article, “HPV-associated head and neck cancer: a virus-related cancer epidemic,” reviews the current understanding of the disease and recognizes an uptick in incidences among a population that has no history of alcohol or tobacco use. In an observation that reinforces Chen’s assertion of the role HPV may play in how cancer cells respond to radiation therapy, the Lancet article points out certain genetic characteristics clearly distinguish HPV-positive cancer from tobacco-related cancer.

Chen reports he will move forward with efforts to better understand the differences in how smokers and never-smokers responded to radiation treatment. The next phase of his research will focus on identification of biological or genetic differences between the populations of smokers and never-smokers.