BACKGROUND: Relatively low rates of chemotherapy receipt have been observed in older patients diagnosed with advanced non-small cell lung cancer (NSCLC) in SEER-Medicare-based studies. However, little is known about variation in first-line NSCLC chemotherapy use in younger patients, health maintenance organization (HMO)-based settings, and for high-cost, novel agents, such as bevacizumab and erlotinib. METHODS: A cohort of 6614 stage IIIB/IV NSCLC patients aged >/= 21 years diagnosed between 2000 and 2007 was identified at four HMOs that participate in the Cancer Research Network (CRN). Demographic, comorbidity, tumor characteristics, and chemotherapy treatment data were included in logistic regression models to identify factors associated with chemotherapy receipt and tests of association examined secular and age-specific variation in first-line chemotherapy regimens. RESULTS: Within 120 days of diagnosis, 3612 (55%) patients received chemotherapy; increasing from 52% of patients diagnosed in 2000 to 59% in 2007 (p<0.001). Receipt was significantly higher for patients aged <65 years (64% versus 46% in >/= 65) and was inversely related to stage and comorbidites (all p<0.001). Carboplatin and paclitaxel were received most frequently. Erlotinib and bevacizumab use in the later years of the study was associated with a significant change in distributions of first-line chemotherapies (p<0.001). CONCLUSIONS: For patients alive 30 days post diagnosis, chemotherapy use was higher in the aged population (>65 years) than previously published estimates, and higher still among younger patients. Chemotherapy use increased over the observation period, and the mix of first-line therapies used changed substantially over time. Of note, novel, high cost treatments were used in first-line therapy prior to FDA approval, increasing significantly throughout the study period. These findings demonstrate the utility of HMO CRN data to augment SEER-Medicare to conduct comparative effectiveness research related to chemotherapy use and the use of specific agents, especially among younger patients.