Metastasis patterns and prognosis in patients with gastric cancer: a Surveillance, Epidemiology, and End Results-based analysis.

Background: Gastric cancer is one of the most commonly diagnosed malignancies, and a majority of patients with gastric cancer are diagnosed at an advanced stage. However, the association between metastatic patterns and survival outcomes in patients with advanced gastric cancer has not been fully explored. In the present study, we aimed to investigate the metastatic patterns and their association with prognosis in patients with gastric cancer. Methods: We collected and reviewed data of patients with metastatic gastric cancer from the Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2015. The Kaplan-Meier method was used to create survival curves, and the Cox proportional regression model was applied to analyze the association between metastatic pattern and prognosis. Results: A total of 10,262 patients were enrolled in the present study. Among them, 4,699 (45.79%) had single-site metastasis, including 3,358 (32.72%) with liver-only metastasis, 699 (6.81%) with bone-only metastasis, 560 (5.46%) with lung-only metastasis, and 82 (0.80%) with brain-only metastasis. Moreover, 1,308 (12.75%) patients had multisite metastases, and 4,255 (41.46%) patients had distant metastases but no other detailed information. The median overall survival for patients with single-site and multisite metastases was 4 and 3 months, respectively. The multivariate Cox regression analysis showed that compared with bone-only metastasis, liver-only metastasis (P<0.001) and lung-only metastasis (P=0.001) were associated with better prognosis. Conclusions: The liver is the most common metastatic site in patients with gastric cancer. N stage, chemotherapy, surgery, and metastatic pattern are independent risk factors associated with prognosis.