Risk of brain metastases in patients with nonmetastatic lung cancer: Analysis of the Metropolitan Detroit Surveillance, Epidemiology, and End Results (SEER) data.

BACKGROUND: Brain metastases (BM) remain an important cause of morbidity and mortality in patients with lung cancer. The current study evaluated population-based incidence and outcomes of BM in patients with nonmetastatic lung cancer.

METHODS: Patients diagnosed with nonmetastatic first primary lung cancer between 1973 and 2011 in the Metropolitan Detroit Surveillance, Epidemiology, and End Results (SEER) registry were used for the current analysis. Age-adjusted odds ratios of developing BM based on various demographic characteristics and histology were calculated with 95% confidence intervals. Adjusted Cox proportional hazard ratios and log-rank tests of Kaplan-Meier survival curves were calculated to evaluate survival differences for non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC).

RESULTS: The incidence of BM in patients with nonmetastatic NSCLC and SCLC was 9% and 18%, respectively. There was variation in the incidence of BM according to NCSLC histology. The incidence of BM was higher in patients aged <60 years for both NSCLC and SCLC, but there were no differences noted by race for either histological group. Female patients with NSCLC were more likely to have BM than male patients. There was variation in the proportion of BM in both patients with NSCLC and SCLC over the three 13-year periods of diagnosis. The risk of death (hazard ratio) was found to be significantly higher for patients with NSCLC with BM, but was not significantly higher in patients with SCLC with BM.

CONCLUSIONS: The incidence of BM in patients with nonmetastatic lung cancer varies according to histology, age, and sex. BM are associated with worse survival for patients with NSCLC but not those with SCLC. Cancer 2016;122:1921-7. © 2016 American Cancer Society.