Abstract 4688: A relationship between environmental tobacco smoke (ETS) and epidermal growth factor receptor (EGFR) mutations in never smoker patients with non-small cell lung cancer

Abstract

Abstract Purpose The etiology of EGFR-mutant lung cancer remains unknown. The high incidence of EGFR mutations are observed in life-time never smokers. We investigated whether the risk factors of lung cancer in never smoker may be associated with a mutant-EGFR dependent carcinogenesis. Especially, we focused on the effect of ETS on EGFR-mutant lung cancer. Patients and Methods We enrolled 179 consecutive never smokers who were newly diagnosed with NSCLC. The history of ETS exposure was obtained with a standardized questionnaire that included exposure period, place, and duration. The nucleotide sequences of exons 18-21 on EGFR gene were determined using nested PCR amplification. Those patients with an exon 19 deletion and exon 21 point mutations were selected as a subgroup with activating mutations for further analysis. Results The median total smoker-year of patients with ETS exposure was higher than that of those without (25 years vs. 15 years; P = 0.002). The incidence of EGFR mutations was significantly lower in patients with ETS exposure than in those without (38.5% vs. 61.4%; P = 0.008). The proportion of exon 19 mutation was lower in patients with ETS exposure (59.6% vs. 81.5%; P = 0.050). In a logistic regression model that adjusted for gender and histology, an adjusted odds ratio (AOR) for the risk of EGFR mutations with exposure to ETS was 0.40 (95% confidential interval [CI], 0.20-0.81; P = 0.011). In quartile groups based on total smoker-year, the AORs for the lowest- to highest-quartile groups were 0.59 (95% CI, 0.23-1.49), 0.50 (0.17-1.50), 0.48 (0.20-1.18), and 0.22 (0.08-0.62) (Ptrend = 0.028). The period and place of ETS exposure had no different effect on the incidence of EGFR mutations. Patients with ETS exposure showed a lower response rate to EGFR tyrosine kinase inhibitors than did patients without ETS exposure (24.6% vs. 44.8%; P = 0.053). Conclusions Exposure to ETS is negatively associated with the incidence of EGFR mutations in lung cancer in never smokers. There was an inverse trend between the cumulative dose of ETS exposure and the frequency of EGFR mutations. A mutant-EGFR-dependent carcinogenesis may be different from a tobacco-smoke-associated carcinogenesis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4688.