Surgical resection of primary tumors improves survival in patients with lung metastases: a population-based SEER analysis.

Background: The lung is a common site for cancer metastasis. Some cancer patients would develop lung metastases throughout the course of their illness. However, choosing surgical resection of the primary tumor (SRPT) or palliative treatment in patients with lung metastases remains controversial. Methods: Lung metastatic patients diagnosed from 2010 to 2016 were selected from the Surveillance, Epidemiology, and End Results (SEER) database. Selected patients were divided into two subgroups (surgery and non-surgery). Further, all the 58 tumor types were classified into 13 subtypes. The clinical and demographic features were examined by the Fisher's exact test, chi-squared test, or z-test. Overall survival (OS) was analyzed using the Kaplan-Meier (K-M) estimator and a log-rank test for each primary tumor type. Multivariable survival analyses of OS were performed using the Cox proportional hazards model. Results: Among the 118,088 patients selected for study, 18,688 (15.83%) patients had undergone surgery. The analyses demonstrated that there was a significant association between SRPT and better OS in patients with lung metastases. The median survival time increased from 4.0 months in the non-surgery group to 19.0 months in the surgery group. Multivariate Cox regression analyses further validated that patients who underwent SRPT had an improved OS. Conclusions: The current study demonstrated that patients with lung metastases can benefit from SRPT. SRPT should be considered in patients with lung metastases. Properly designed prospective randomized clinical trials would be required to further verify the conclusion.