Primary tumor response to chemoradiotherapy in limited-disease small-cell lung cancer correlates with duration of brain-metastasis free survival

The brain represents a crucial site of failure in limited-disease (LD) small-cell lung cancer (SCLC). However, no data about correlation between response of primary tumor to chemoradiotherapy (CRT) and brain metastases (BM)–free survival time in LD SCLC are available. A total of 125 LD SCLC patients with initial performance score of WHO 2–3 were successfully treated with CRT. Prophylactic cranial irradiation (PCI) was applied after complete response. Cranial MRI was performed in patients at initial diagnosis, in complete responders before PCI, and by individual symptoms. A total of 30 patients (24 %) developed BM after CRT; 5 of them (17 %) developed BMs after PCI. Ten patients (33 %) show BM after complete, 5 (17 %) after partial and 15 (50 %) after non-response of primary tumor (p < 0.0001) to applied CRT. BM-free survival time for the entire cohort was 298 days (95 CI: 218–377): 567 days (95 CI: 322–811) in complete, 298 days (95 CI: 244–351) in partial and 252 days (95 CI: 217–286) in non-responders (p < 0.0001). PCI prolonged BM-free survival time in complete responders: 640 days (95 CI: 483–796) with PCI versus 482 days (95CI: 111–926) without PCI (p = 0.047) versus 273 days (95 CI: 243–302) for partial and non-responders. The duration of BM-free survival was shown to correlate with long-term outcome in the Pearson and Spearman’s tests (p < 0.0001). The response of primary tumor to CRT strongly affects duration of BM-free survival in LD SCLC and should be considered by planning of the timing of PCI.