Prophylactic Cranial Irradiation in Extensive Stage Small Cell Lung Cancer: Outcomes at a Comprehensive Cancer Centre

The role of prophylactic cranial irradiation (PCI) remains controversial in extensive stage small cell lung cancer (ES-SCLC) with the publication of 2 randomized control trials demonstrating differing outcomes in overall survival. The aim of this study is to determine the impact of PCI on survival and the development of brain metastasis while addressing the disparate use of postchemotherapy brain imaging in the aforementioned trials.

The medical records of 397 consecutive patients with ES-SCLC between Jan. 1, 2005 and Dec. 31, 2011 were retrospectively reviewed. In those eligible patients (n = 155) without baseline brain metastases and who had at least a partial response to chemotherapy, overall survival and time to brain metastasis were estimated using the Kaplan-Meier method comparing patients receiving PCI or not, using both univariate and multivariate analyses. Patients were stratified by their receipt of initial postchemotherapy brain imaging. Follow-up did not include serial brain imaging, which was performed when clinically indicated. Differences between the groups with covariates were analyzed using χ² statistics and Student's t-tests.

By multivariate analysis, statistically significant predictors of overall survival were the presence of extrathoracic metastases, performance status and use of PCI. There was a statistically significant difference in overall survival (HR 0.55; 95% CI: 0.39-0.77; P = .0005) and time to brain metastasis (HR 0.40; 95% CI: 0.23-0.66; P = .0004) with the use of PCI. Median survival for the PCI and non-PCI groups was 13.5 and 8.5 months respectively. A survival difference with PCI was observed in both patients that received postchemotherapy brain imaging (HR 0.55; 95% CI: 0.35-0.88; P = .012) and those who did not (HR 0.48; 95% CI: 0.29-0.77; P = .0025).

PCI in the setting of at least a partial response to chemotherapy was found to have a survival benefit and prolongation of the time to development of brain metastases, when factoring in the use of initial postchemotherapy but not routine surveillance brain imaging.