Japanese Ethnicity Compared with Caucasian Ethnicity and Never-Smoking Status Are Independent Favorable Prognostic Factors for Overall Survival in Non-small Cell Lung Cancer: A Collaborative Epidemiologic Study of the National Hospital Organization Study

BackgroundWe previously reported that Asian ethnicity was a favorable prognostic factor for overall survival (OS) in non-small cell lung cancer (NSCLC). In this study, we performed a combined data analysis from a Japanese Cancer Registry and a regional California Cancer Registry to further validate this observation.MethodsRetrospective population-based analysis of Japanese and Caucasian patients with NSCLC with known smoking status from the Japanese National Hospital Organization Study Group for Lung Cancer and a Southern California Regional Cancer Registry between 1991 and 2001.ResultsA total of 15,185 Japanese and 13,332 US Caucasian patients were analyzed. Median age of Japanese patients was 68 years compared with 69 years for Caucasian patients (p < 0.0001). A total of 29.3% of Japanese compared with 7.3% Caucasian patients were never-smokers. Never-smoking status conferred significant improved OS for Japanese (p < 0.0001) and a trend for improved OS for Caucasian patients (p = 0.1282). Univariate analysis revealed Japanese patients with stage III (versus Caucasian; hazard ratio [HR] = 0.830, 95% confidence interval [CI]: 0.789-0.873, p < 0.0001) and IV disease (versus Caucasian; HR = 0.955, 95% CI: 0.915-0.997, p = 0.0369) had improved OS compared with Caucasian patients. Multivariate analysis revealed Japanese ethnicity (versus Caucasian; HR = 0.937, 95% CI: 0.898-0.978, p = 0.0028) and never-smoker status (versus ever-smoker; HR = 0.947, 95% CI: 0.909-0.987, p = 0.0104) to be independent favorable factors for OS in addition to younger age, female gender, early stage, and treatment received (surgery, radiation, and chemotherapy).ConclusionsJapanese ethnicity when compared with Caucasian ethnicity and never-smoker status are independent favorable prognostic factors for OS in NSCLC.