Smoking intensity, oxidative stress and chemotherapy in nonsmall cell lung cancer: a correlated prognostic study.

Cigarette smoking is a well known environmental risk factor for lung cancer; furthermore it can also enhance lung carcinogenesis by free radical mediated reactions. In addition smoking affects the rates of metabolism of several drugs and may contribute to poor cancer survival. The purpose of the present work, therefore, was to see the relationship of different smoking intensities with oxidative stress and survival after platinum based chemotherapy in non-small cell lung cancer (NSCLC). The oxidative stress levels (LPO, NO, SOD, and GSH) of 144 control subjects and 203 advanced stage NSCLC patients were assessed at day '0', after the 3rd and 6th cycle of chemotherapy. Pack year (PY) was stratified in groups (1-20, 21-50, > 50) for further analysis. Groups were compared using repeated measured ANOVA, while survival curves were compared by Kaplan-Meier methods. Oxidative stress levels of smokers were significantly high (p < 0.01 or p < 0.05) as compared to non-smoker at pretreatment, after the 3rd cycle and 6th cycle of chemotherapy but not well correlated with the PY exposures. Overall mean survival of smoker patients were significantly low when compared to non-smokers. The survival of > 50 PY group was significantly lowered (p < 0.01) as compared to others PY groups, indicating that survival after chemotherapy in smoker NSCLC patients may be dependent on their PY exposures. In conclusion, smoking is a bad prognostic factor in lung cancer therapy, besides its role in oxidative stress, and poor survival. Therefore, this factor can be used in patient selection for chemoprevention.