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 Group for Lung Cancer (NHSGLC) in Japan and a Southern California Regional Cancer Registry Databases

Background: We 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. Methods: Retrospective 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. Results: A 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). Conclusions: Japanese ethnicity when compared with Caucasian ethnicity and never-smoker status are independent favorable prognostic factors for OS in NSCLC.