Smoking history impacts success of lung cancer therapy

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Patients with non-small cell lung cancer (NSCLC) who have never smoked respond better to chemotherapy and live longer than those with a history of smoking, even if they quit long before treatment, according to a report in the June 1st issue of Cancer.

"This study shows just why primary prevention for smoking is so important," Dr. Anne S. Tsao from M. D. Anderson Cancer Center in Houston, who led the study, stated in an interview with Reuters Health.

Prior studies that have looked at the impact of smoking history on outcome of lung cancer therapy have yielded mixed results. Being mindful of the shortcomings of prior studies, Dr. Tsao's team reviewed the medical records of 1,370 NSCLC patients treated with chemotherapy (n = 497) or chemoradiation (n = 873) to assess associations between smoking and treatment response and survival.

In the chemotherapy group, 16% of patients had never smoked, 42% were former smokers, and 42% were current smokers (22% continued to smoke during chemotherapy).

In this group, never-smokers had higher response rates than former and current smokers (19% vs 8% and 12%, respectively) and lower rates of progressive disease (49% vs 65% and 66%, respectively). Never-smokers also had higher overall survival rates (p < 0.0001) than former and current smokers.

Active smoking during chemotherapy did not seem to influence outcome.

In the chemoradiation group, 6% were never-smokers, 45% were former smokers and 49% were current smokers. "Surprisingly," Dr. Tsao and colleagues write, in this group, multivariate analysis revealed no adverse effect of smoking on treatment response or overall survival.

In fact, the patients who had the worst outcome were those who quit smoking right before chemoradiation. This finding "most likely is related to the fact that these patients became too ill to continue smoking," the authors suggest.

Summing up, Dr. Tsao said: "This study basically shows that if you've never smoked, even if you develop lung cancer, you will respond much better to therapy and have improved survival, and that the damage from smoking is pretty significant and it doesn't seem to impact, whether you quit or not, what your response rate is to chemotherapy and what your survival is."

Continued efforts to prevent people from taking up smoking remain "a critical public health issue," she and her colleagues conclude.