PUB040 Treatment Response and Prophylactic Cranial Irradiation Are Important Prognostic Factors in LD SCLC Patients Staged with cMRI

Abstract

The role of prophylactic cranial irradiation (PCI) in LD SCLC has proven to significantly decrease the incidence of brain metastases (BMs) with only modest improvement of survival. To evaluate an exact impact of PCI, we reviewed 184 LD SCLC patients treated with definitive chemoradiotherapy (CRT). PCI was applied in the partial and complete responders exclusively when contrast enhanced cranial magnetic resonance imaging (cMRI) before and after primary treatment showed no BMs. Correlation between application of PCI and time to progression (TTP) as well as overall survival (OS) was analysed. Kaplan-Meier analysis and Cox regression were used to describe survival within subgroups defined by application of PCI. Concurrent and sequential CRT was applied in 71 (39%) and 113 (61%) patients, respectively. Metachronous BMs were detected in 58 (32%) patients. PCI was applied in 71 (39%) partial and complete responders. 15 (21%) patients developed BMs after PCI. Median TTP and OS in the therapy responders treated with PCI were 29 and 28.6 compared to 12.7 (range: 10.1 – 16.3) (p < 0.0001) and 13.8 (range: 11.4 – 16.1) (p < 0.0001) months in the rest of patient cohort, respectively. The effect of PCI was independent of gender. In the multivariate analysis, application of PCI in responders was a variable that significantly correlated with TTP (HR 2.16 CI HR 1.37-3.42, p < 0.001) and OS (HR 1.89 CI HR 1.37-2.63, p < 0.0001) after adjustment for other patient- and treatment-related prognostic factors. In LD SCLC patients comprehensively staged with cMRI and treated with CRT, treatment response and application of PCI strongly correlated with prolonged TTP and OS.