Impact of second hand smoke (SHS) exposure on the likelihood of mutations in epidermal growth factor receptor (EGFR) gene in patients with non-small cell lung cancer (NSCLC) who had never smoked

Abstract

7633 Background: The presence of EGFR mutations in NSCLC has strongly associated with never-smoking history. SHS exposure is associated with higher risk of lung cancer. We have conducted this study to evaluate the association between SHS exposure and likelihood of mutations in EGFR gene in NSCLC patients who had never smoked. Methods: SHS exposure information from a total of 93 never smokers (<100 lifetime cigarettes) with newly diagnosed primary NSCLC was obtained using a standardized questionnaire. Patients were asked whether they were regularly exposed to SHS at home or work places, respectively. Nucleotide sequencing of the kinase domain of EGFR (exons 18 to 21) was performed using nested PCR amplification of individual exons. Results: Patient characteristics (n=93) included median age 57 years; female (n= 81); adenocarcinoma ± bronchoalveolar carcinoma (n= 82); EGFR mutation (1 mutation in exon 18 G719, 31 in-frame deletions in exon 19, 10 mutations in codon 858 in exon 21). Fifty-two (55.9%) of the patients reported having been exposed to SHS, including 46 (49.5%) exposed at home and 13 (14.0%) exposed at work. The incidence of EGFR mutations was not associated with female gender and adenocarcinoma histology. Patients with SHS exposure showed a trend towards lower incidence of EGFR mutations (36.5% vs. 56.1%, P= 0.060) and a significantly lower incidence of deletion mutations in exon 19 (57.9% vs. 87.0%, P= 0.033). When the incidence of EGFR mutations was compared, no difference between SHS exposure at home and work places was found. No significant differences were found for other clinicopathological factors according to SHS exposure. Conclusions: Our results indicate weak evidence of relationship between likelihood of mutation in EGFR gene and SHS exposure. The deletion mutations in exon 19 were significantly less common in patients with SHS exposure. No significant financial relationships to disclose.