Study objectives: The prevalence of epidermal growth factor receptor (EGFR) mutations in gefitinib-naive lung cancer patients is higher in adenocarcinomas, in women, and in Japanese. To further investigate the prevalence of EGFR mutations in relation to ethnic and geographic factors, we evaluated EGFR mutations in a series of Taiwanese patients with primary lung adenocarcinomas who had never been treated with gefitinib.
Design and methods: We retrospectively studied 35 primary lung adenocarcinoma samples for mutations in the tyrosine kinase domain of EGFR; exons 18, 19, and 21 were analyzed by nested polymerase chain reaction and automated sequencing. Clinicopathologic information was obtained from patient records and pathology reports. Correlation between EGFR mutations and patient characteristics, including sex, smoking history, and pathologic subtypes, were evaluated by using the χ2 test and logistic regression analysis.
Results: Heterozygous EGFR mutations were detected in 17 of 35 patients (48%). Missense mutations in exon 21 (13 of 17 patients, 76%) were the most frequent mutations detected. EGFR mutations were more frequent in women (13 of 18 patients [72%]) than in men (4 of 17 patients [23%]; p = 0.004), more frequent in nonsmokers (14 of 21 patients [66%]) than in current smokers (3 of 14 patients [21%]; p = 0.009), and when any degree of bronchioloalveolar carcinoma (BAC) was present (14 of 21 patients [66%]) compared with pure adenocarcinoma (3 of 14 patients [21%]; p = 0.009). Logistic regression analysis demonstrated that female gender (odds ratio [OR], 10.913; 95% confidence interval [CI], 1.778 to 66.97; p = 0.01) and BAC, including adenocarcinomas with any bronchioloalveolar features (OR, 9.708; 95% CI, 1.464 to 64.393; p = 0.019), were significantly associated with EGFR mutations.
Conclusions: In our series, female sex and bronchioloalveolar pathologic subtype predicted the presence of EGFR mutations in lung adenocarcinomas, and the high frequency of EGFR mutations supports the hypothesis that genetic backgrounds and/or environmental factors may affect the pathogenesis of certain lung cancers.