Second Hand Smoke Exposure and Survival in Early-Stage Non–Small-Cell Lung Cancer Patients

Abstract

Second hand smoke (SHS) exposure is associated with higher risk of lung cancer. However, the role of SHS in lung cancer survival is not clear. We examined the association between self-reported SHS exposure before diagnosis and overall survival and recurrence-free survival in 393 early-stage non-small-cell lung cancer patients. SHS exposure was analyzed by both duration and location of exposure using log-rank test and Cox proportional hazard models, adjusting for covariates including pack-years of smoking. The median follow-up time was 66 months (range, 0.2-140 months). There were 135 recurrences and 213 deaths. The 5-year overall survival rates were 71% [95% confidence interval (95% CI), 62-81%], 61% (51-72%), 49% (38-60%), and 47% (37-58%), respectively, for patients with the lowest to highest quartile of SHS exposure durations (P < 0.001, log-rank test), with the adjusted hazard ratio (AHR) of 1.57 (95% CI, 1.02-2.41) for the highest versus lowest quartile of SHS exposure durations (P(trend) = 0.04). For different SHS exposure locations, a stronger association was found for SHS exposure at work (AHR of the highest versus lowest quartile, 1.71; 95% CI, 1.12-2.61; P(trend) = 0.03) than for exposure at home (AHR, 1.26; 95% CI, 0.86-1.86; P(trend) = 0.20) or leisure places (AHR, 1.28; 95% CI, 0.83-1.95; P(trend) = 0.16). Similar associations were observed when SHS exposure durations were dichotomized into two or three groups and between SHS exposure and recurrence-free survival. SHS exposure is associated with worse survival in early-stage non-small-cell lung cancer patients, especially for SHS exposure at the work.