Lung Cancer in Non-Smokers: Clinicopathological and Survival Differences from Smokers

Abstract

Background Lung cancer in non-smokers is a clinically distinct entity based on unique epidemiology, clinicopathology, genetics, treatment response, and outcome. Data from Indian centres are scarce. The objective of this study was to compare the frequency, clinical characteristics, driver mutations, and survival of non-smoking and smoking lung cancer patients treated at a tertiary cancer centre in North India. Methodology Two years of data on 724 consecutive lung cancer patients were assessed. Clinical, demographics, smoking history, and EGFR and ALK mutation test results were collected. Descriptive and inferential statistics were applied. Survival analysis was performed using the Kaplan-Meier method. Results Non-smokers comprised 40.9% of the study sample. Non-smokers were more likely than smokers to experience disease onset at a younger age (P = 0.004) and metastasis (P < 0.001). The tumor histology showed significant differences (P < 0.001), with non-smokers more likely to be diagnosed with adenocarcinoma (77.4%), while squamous and small cell histologies were commonly found among smokers (37.6% and 13.8%, respectively). The EGFR mutation and ALK rearrangement rates in the cohort were 23.3% and 10.1%, respectively, and were more frequent in non-smoking patients. Overall, 10-year survival was 7%, with a significantly better survival rate of non-smokers than smokers (median survival time of 15.13 vs 10.17 months; P = 0.012). Conclusions About four out of 10 patients diagnosed with lung cancer at our centre were non-smokers. They were more often young, diagnosed at an advanced stage, with predominantly adenocarcinoma histology, and had a threefold higher frequency of EGFR mutations than smokers. In our cohort, non-smokers appear to be a targetable group with better survival than smokers.