East meets West: ethnic differences in epidemiology and clinical behaviors of lung cancer between East Asians and Caucasians

Lung cancer is the leading cause of cancer death worldwide, with large variation of the incidence and mortality across regions. Although the mortality of lung cancer has been decreasing, or steady in the US, it has been increasing in Asia for the past two decades. Smoking is the leading cause of lung cancer, and other risk factors such as indoor coal burning, cooking fumes, and infections may play important roles in the development of lung cancer among Asian never smoking women. The median age of diagnosis in Asian patients with lung cancer is generally younger than Caucasian patients, particularly among never-smokers. Asians and Caucasians may have different genetic susceptibilities to lung cancer, as evidenced from candidate polymorphisms and genome-wide association studies. Recent epidemiologic studies and clinical trials have shown consistently that Asian ethnicity is a favorable prognostic factor for overall survival in non-small cell lung cancer (NSCLC), independent of smoking status. Compared with Caucasian patients with NSCLC, East Asian patients have a much higher prevalence of epidermal growth factor receptor (EGFR) mutation (approximately 30% vs. 7%, predominantly among patients with adenocarcinoma and never-smokers), a lower prevalence of K-Ras mutation (less than 10% vs. 18%, predominantly among patients with adenocarcinoma and smokers), and higher proportion of patients who are responsive to EGFR tyrosine kinase inhibitors. The ethnic differences in epidemiology and clinical behaviors should be taken into account when conducting global clinical trials that include different ethnic populations.