Prophylactic cranial irradiation is associated with improved survival following resection for limited stage small cell lung cancer.

Background: Brain metastases are a major cause of mortality in patients with small cell lung cancer (SCLC). Prophylactic cranial irradiation (PCI) may improve survival among patients that respond to chemotherapy. Less is known about the outcomes of PCI following surgical resection of SCLC. The purpose of this study was to determine if patients who underwent initial surgical resection of SCLC benefit from PCI.

Methods: Adult patients in the National Cancer Database (NCDB) who underwent complete resection for primary, non-metastatic SCLC between 2004 and 2015 were identified. Patients that received preoperative chemotherapy or who did not receive appropriate adjuvant chemotherapy were excluded. Patients were grouped by treatment with or without cranial radiation within 8 months of resection. Survival was estimated using Kaplan-Meier and Cox multivariable analysis, adjusting for patient and tumor characteristics.

Results: A total of 859 patients met inclusion criteria (202 received PCI and 657 did not). Kaplan-Meier analysis demonstrated that patients treated with PCI had significantly improved survival compared to no PCI (5-year survival 59% 50%, logrank P=0.0038). Multivariable cox models confirmed a significantly decreased hazard of death for patients receiving PCI (HR: 0.70, 95% CI: 0.55-0.89, P=0.003). In subset analyses, PCI was associated with significantly improved survival for node positive patients, but not node negative patients.

Conclusions: PCI is associated with increased survival for patients following surgical resection of SCLC. Patients with positive lymph nodes appear to benefit the most, while it remains unclear if patients with negative lymph nodes derive a benefit. Further study is warranted to clarify which subsets of patients should be treated with PCI.