The survival analysis of different metastasis sites for 332 patients of extensive stage small cell lung cancer

Objective: To investigate the effects of different metastatic, sites on the prognosis of extensive-stage small cell lung cancer (SCLC). Methods: A retrospective analysis was performed among 322 patients pathologically or cytologically diagnosed with extensive-stage SCLC (stage IV defined by the seventh edition of the American Joint Committee on Cancer) who were admitted to our hospital from 2011 to 2015. In those patients, 246 had primary lesions with distant metastasis and 76 primary lesions with non-regional lymph node metastasis; 261 had single-organ metastasis and 61 multi-organ metastases. Survival rates were calculated using the Kaplan-Meier method. Between-group comparison of the survival was made by the log-rank test. A multivariate prognostic analysis was made by the Cox proportional hazard model. Results: In all the patients, the median survival time (MST) was 11.7 months; 1- and 2-year overall survival (OS) rates were 47.9% and 19.5%, respectively. The patients with single-organ metastasis had significantly longer MST and significantly higher 1- and 2-year OS rates than the patients with multi-organ metastases (12.4 vs. 8.9 months; 52.5% vs. 30.5%; 21.9% vs. 11.2%; P = 0.014). In the patients with single-organ metastasis, those with liver metastasis had the worst prognosis with a MST of 8.5 months, while those with non-regional lymph node metastasis had the best prognosis with a MST of 14.5 months (P = 0.001); there was no significant difference in the prognosis between patients with metastasis to different organs other than the liver (P = 0.139). In the patients with multi-organ metastases, those with liver metastasis and bone metastasis had the worst prognosis (P = 0.016, 0.006); there was no significant relationship between brain metastasis and the prognosis of extensive-stage SCLC with multi-organ metastases (P = 0.995). There was no significant difference in the prognosis between those with liver metastasis only and multi-organ metastases (P = 0.862). Conclusions: Liver metastasis predicts the worst prognosis in patients initially diagnosed with extensive-stage SCLC and single-organ metastasis. Liver metastasis and bone metastasis predict the worst prognosis in patients with multi-organ metastases. Brain metastasis has no significant effect on the prognosis. There is no significant difference in the prognosis of extensive-stage SCLC between patients with single-and multi-organ metastases once liver metastasis occurs. (authors)