Prophylactic cranial irradiation in patients ≥ 70 years old with limited stage small cell lung cancer: A Surveillance, Epidemiology, and End Results analysis.

Abstract

7589 Background: Prophylactic cranial irradiation (PCI) improves survival in patients with limited stage small cell lung cancer (SCLC) who have a complete response to chemotherapy and radiation (RT). Yet in clinical practice, concerns exist regarding PCI-related toxicity and the extent of benefit in elderly patients. This exploratory analysis evaluates the effect of PCI on survival among patients ≥ 70 years old. Methods: Using the Surveillance, Epidemiology, and End Results (SEER) database, we identified 4,003 patients ≥70 years old with localized or regional SCLC diagnosed between 1988 and 1997. Patients with no brain RT information (n=974) were excluded. Patients with overall survival (OS) <6 months (n=1103) were also excluded to eliminate patients with an aggressive disease course and minimize selection bias. Survival rates for patients who received brain RT versus no brain RT were estimated by the Kaplan Meier method and compared with the Log-rank test. A Cox proportional hazards model was further fitted to estimate the effect of brain RT on OS after adjusting for age, race, gender, and stage. Results: Of the 1926 patients included, the median age was 75 years (range, 70-94). The majority of patients were white (68%) and male (52%). According to SEER Historic Stage A, 68% of patients had regional stage and 32% had localized stage. One-hundred and thirty-eight patients (7.2%) received brain RT. Patients treated with brain RT were younger at diagnosis (p<0.01) and more likely to have regional stage disease (p=0.02). Five-year OS was 11.6% (95% CI: 6.9-17.6) among patients who received brain RT versus 8.6% (95% CI: 7.32-9.91) among patients who did not (p=0.03). Younger age, female gender, white race, and localized stage were also significant factors associated with improved OS. On multi-variable analysis, receipt of brain RT remained an independent predictor of OS (HR 0.825, 95% CI: 0.69-0.98, p=0.03). Conclusions: The receipt of brain radiotherapy is associated with improved overall survival in patients ≥70 years old with localized or regional stage SCLC, suggesting the benefit of PCI is maintained in the elderly population.