Although not a surprise, a study has shown that patients who continue to smoke while undergoing radiation treatments for head and neck cancer fare significantly worse than those who quit smoking before therapy.
The authors of the study, published in the February issue of the International Journal of Radiation Oncology•Biology•Physics, note that although the association between tobacco smoking and head and neck cancers has long been established, there had been little data until now showing whether continued smoking during treatment affects prognosis.
“I've always told patients, ‘You should really stop smoking,’ but I had no tangible evidence to use to convince them that they would be worse off if they continued to smoke,” Allen Chen, MD, lead author of the study and residency training program director at the University of California, Davis, School of Medicine, said in a news release.
“I wanted concrete data to see if smoking was detrimental in terms of curability, overall survival, and tolerability of treatment. We showed that continued smoking contributed to negative outcomes with regard to all of those.”
He and his colleagues reviewed the medical records of 101 patients with newly diagnosed squamous cell carcinoma of the head and neck who continued to smoke during radiation therapy and matched those patients to others who had quit prior to starting radiation therapy for their head and neck cancers. Matching was based on primary disease site, gender, smoking duration, stage of disease, radiation dose, other treatment (surgery and chemotherapy), and date of initiation of radiation therapy.
A total of 55% of patients who had quit smoking prior to treatment were still alive five years later, compared with 23% of those who continued to smoke. The poorer outcomes for persistent smokers were reported for both patients who had surgery prior to radiation therapy and patients who had radiation alone.
Similarly, 53 of the patients who still smoked experienced disease recurrence, compared with 40 patients in the control group. Active smokers also experienced more complications of treatment, such as scar tissue development, hoarseness, and difficulties with food intake.
Dr. Chen noted that additional research will be needed to explain these differences in outcomes. One theory, though, is that smoking deprives the body of much needed oxygen: “Radiation therapy requires oxygenation for the production of free radicals, which attack cancer cells,” he said.
In addition, patients unable to quit may also have non-cancer-related medical and psychosocial problems that could possibly contribute to shorter survival.
“Those who continue to smoke even after a diagnosis of head and neck cancer are likely to be at higher risk for alcohol abuse, have less social support, and have lifestyles associated with high-risk health behaviors. A diagnosis of cancer is emotionally devastating, and a lot of patients are reluctant to entertain the idea of smoking cessation. Many patients can't or won't connect the dots, and unfortunately, our data is showing that by continuing to smoke, they are more likely to gamble away the possibility of cure.”