BACKGROUND: The treatment, prognosis, and outcomes of young lung cancer patients have not been fully explored. In addition, there is a pressing need to characterize this subgroup of patients, because there is a trend of increasing incidence in younger patients from Europe and Japan. METHODS: Consecutive, nonselected young patients (<45 years old) with pathologically diagnosed lung cancer treated at 175 qualified hospitals in the greater Shanghai area were included in this analysis. Incidence, prognostic factors, and treatment outcome of lung cancer patients from 2002 to 2006 were documented. A comparison with lung cancer patients of any age was also made. RESULTS: A total of 12,380 patients with nonsmall cell lung cancer were registered. Among them, 652 patients were between 15 and 45 years old. One-year, 3-year, and 5-year survival rates of lung cancer patients younger than 45 years were 49.87%, 26.68%, and 23.12%, respectively. TNM stage, treatment hospital (tertiary vs community hospital), sex, and cancer histology were confirmed as independent prognostic factors. Compared with lung cancer patients of any age in Shanghai, the percentage of adenocarcinoma in the young male subgroup was significantly higher (63.77% vs 43.19%, P < .001). Interestingly, median survival time of young lung cancer patients was similar with that of lung cancer patients of any age, but was significantly shorter than the median survival of middle-aged patients (45-60 years old). CONCLUSIONS: Median survival of the middle-aged group (45-60 years) was significantly longer than the young group (<45 years) and the old group (>60 years). Therefore, aggressive treatment modalities should be strongly considered for young lung cancer patients. © 2010 American Cancer Society.