Smoking is a major risk factor causing lung cancer and chronic obstructive pulmonary disease. Smoking status has been known to be an independent prognostic factor of lung cancer patients. We conducted this study to know if individual susceptibility to smoking is related to the survival in locally advanced or advanced non-small cell lung cancer (NSCLC) patients.
From our prospective cohort of the lung cancer, after excluding non-smokers, we included locally advanced or advanced NSCLC patients who were completed with treatment(n=186) or treated only conservatively(n=151) in this study. All patients were performed pulmonary function testing at the time of diagnosis. We estimated individual susceptibility to smoking using a formula of (100-%predicted FEV1)/pack-year and categorized it by quartile based on the distribution among study subjectsThe statistical analysis of the survival data was performed using SAS program (version 8.1). The duration of median survival were defined as the time from diagnosis to death attributed to lung cancer and that were estimated by Kaplan-Meier method. The difference of survival curve among subgroups were evaluated by log-rank test. To evaluate the effect of susceptibility to smoking on survival was prognosis, Cox proportional hazard regression analysis was performed.
Clinical stage of the patients was IIIA in 65(19.3%), IIIB in 120(35.6%) and IV in 152(45.1%). The median survival time was 13.2months(95% CI: 11.9-15.0 months) for treatment group and 4.9months(95% CI: 3.8-6.5 months) for conservative care group (P<0.001). In log-rank test survival time were significantly different according to age, sex, body weight loss (>5%), %predicted FEV1, clinical stage and individual susceptibility to smoking(P<0.005, 0.036, <0.001, 0.006, <0.001 and <0.001, respectively). The hazard ratio adjusting covariates among patients of highest quartile of susceptibility to smoking was 1.90(95% CI: 1.49-2.38).
Therefore we suggest that individual susceptibility to smoking is an independent prognostic factor of stage III and IV NSCLC patients.
This study may be first of showing individual susceptibility to smoking is an independent prognostic factor of locally advanced or advanced NSCLC patients.
Jeong-Seon Ryu, None.