Prognostic value of site-specific metastases in lung cancer: A population based study

Background: Studies on prognosis of different metastasis sites in patients with lung cancer are limited. The aim of present study was to investigate the prognostic value of metastases sites among patients with metastatic lung cancer. Methods: Between 2010 and 2014, patients diagnosed with metastatic lung cancer were selected using the Surveillance, Epidemiology, and End Results (SEER) database. Kaplan-Meier methods were adopted and multivariable Cox regression models were built to compare the prognosis of different metastasis sites. Results: A total of 54,697 eligible patients were identified, including 10,945 (20.0%) patients had isolated bone metastases, 8,294(15.2%) with isolated brain metastases, 5,677(10.4%) with isolated liver metastases, 9,430(17.2%) with isolate lung metastases, and 20,351(37.2%) with multiple organ metastases. The percentage of bone, brain, liver, lung and multisite metastases were 22.3%, 15.4%, 6.1%, 20.1% and 36.1% for non-small cell lung cancer (NSCLC), 12.5%, 14.3%, 24.3%, 7.9%, and 40.9% for small cell lung cancer (SCLC), the difference was statistical(P<0.001). In univariate and multivariable analysis, patients with liver metastases demonstrated a statistically significant disadvantage in cause-specific survival, while those with lung metastases have reduced risk of died of metastases when compared with brain metastases(P<0.001). The difference was consistent when make subgroup analysis in both NSCLC and SCLC(P<0.001). Conclusions: In patients with distant metastases, those with liver metastases have the poorest survival, whereas those with lung metastases have the best survival. Therefore, we should take into consideration of such discrepancy when making treatment strategies.