Epidermal Growth Factor Receptor Mutations in Japanese Men with Lung Adenocarcinomas

Background: Epidermal growth factor receptor (EGFR) mutations play a vital role in the prognosis of patients with lung adenocarcinoma. Such somatic mutations are more common in women who are non-smokers with adenocarcinoma and are of Asian origin. However, to our knowledge, there are few studies that have focused on men. Materials and Methods: One hundred and eighty-four consecutive patients (90 men and 94 women) of resected lung adenocarcinoma were studied retrospectively. Results: EGFR mutations were positive in 48.9% and negative (wild type) in 51.1%. Overall mutation was significant in women (66.0% vs. 32.2%) compared with men (p<0.001). For overall patients, EGFR mutation status was associated with gender, pStage, pT status, lepidic dominant histologic subtype, pure or mixed ground-glass nodule type on computed tomography and smoking status. However, in men, EGFR mutation status was only associated with lepidic dominant histologic subtype and not the other variables. Interestingly, the Brinkman index of men with mutant EGFR also did not differ from that for the wild type ($680.0{\pm}619.3$ vs. $813.1{\pm}552.1$ p=0.1077). Conclusions: The clinical characteristics of men with lung adenocarcinoma related to EGFR mutation are not always similar to that of overall patients. Especially we failed to find the relationship between EGFR mutations and smoking status in men.