Statistical analysis
The study focused on the North Indian population and included age, gender, and smoking behavior information. The Chi-square goodness-of-fit test was applied to see if the cases followed Hardy-Weinberg equilibrium. The odds of lung carcinoma risk were studied using MedCalc Statistical Software (version 14.8.1 MedCalc Software, Ostend, Belgium). Descriptive data are presented as median, mean ± standard deviation (SD), or number/ percentages. The odds ratio (OR) with the 95 % confidence interval (CI) evaluated using the logistic regression analysis for any toxicity. All the patients’ overall survival (OS) was calculated from day one of chemotherapy to death or the last follow-up date. The univariate Kaplan-Meir method assessed OS time using log Rank p-value and median OS time. After adjusting for other factors, multivariate Cox regression analysis was used to assess the independent effect of polymorphism on overall survival. In all analyses, a p-value of <0.05 was considered significant.
Furthermore, the recursive partitioning strategy accounted for high-order gene interactions. This method generates the initial split by considering the critical factor determining the patients’ overall survival. Survival analysis trees (STREE) application was used to generate the decision tree (http://c2s2.yale.edu/software/stree). The log-rank approach was used as the splitting method. The generated tree was binary, with each terminal node representing a subset of individuals with a specific genotypic combination, thus displaying a range of survival times and prognosis. Multivariate cox proportional hazard analysis was used to determine the HRs and 95% CIs for every terminal node, adjusted for gender, age, histology, ECOG, KPS, stage, and regimen.Toxicity in the lung cancer patients was assessed according to standard National Cancer Institution Criteria 3.0 (http://ctep.cancer.gov). Maximum attention was paid to hematological toxicity such as neutropenia, anemia, leukopenia and thrombocytopenia, gastrointestinal toxicity nephrotoxicity. Severe toxicity or severe event consisted of grade 3 or 4 hematologic toxicity and grade 1–4 nephrotoxicity. With severe hematologic toxicity, the subsequent treatment was postponed until recovery to grade 1 or grade 0. With grade 3 and 4 gastrointestinal toxicity, the doses of each drug were reduced by 25%. If creatinine clearance decreases to within the range of 59−41 ml min−1, platinum was reduced by 25%. If creatinine clearance decreases below 40 ml min−1, platinum was stopped. Clinical data has been systematically recorded during treatment.