Clinicopathological Characteristics and Prognosis of cT1N0M1 Gastric Cancer: A Population-Based Study

Background. Distant metastasis of early gastric cancer is a rare subgroup and poorly understood. The present study is aimed at summarizing the clinicopathological characteristics, prognosis, and management of clinical T1N0M1 (cT1N0M1) gastric cancer. Method. Between 2004 and 2015, patients diagnosed with cT1N0M1 gastric cancer were retrospectively analyzed using the Surveillance, Epidemiology, and End Results (SEER) database. Results. A total of 1093 cT1N0M1 gastric cancer patients were identified. 49 patients (4.5%) received cancer-directed surgery, and 113 patients (10.4%) were managed with radiotherapy. Compared with the other stage IV diseases, a relatively high proportion of black population (19.9% vs. 15.8%), patients older than 60 years (63.1% vs. 57.8%), and adenocarcinoma (59.5% vs. 55.9%) were observed in the cT1N0M1 gastric cancer subgroup. Besides that, patients with cT1N0M1 had the characteristics of less poor differentiated or undifferentiated (54.3% vs. 61.7%). Patients with cT1N0M1 had worse cancer-specific survival (CSS) and overall survival (OS) as compared to the other metastatic gastric cancer patients (CSS: p=0.002, OS: p=0.001 for log-rank test). Intriguingly, patients with cT1N0M1 had poor prognosis as compared to patients with cT1N+M1 (CSS: p=0.015, OS: p=0.007 for log-rank test). The 3-year and 5-year CSS for patients with cT1N0M1 were 5.7% and 4.0%, respectively. The addition of surgery resulted in improved CSS (p<0.001 for log-rank test) while radiotherapy was not associated with CSS (p=0.756 for log-rank test) in patients with cT1N0M1. A multivariate Cox analysis showed that surgery (HR=0.378, 95% CI: 0.255-0.562) and patients younger than 60 (HR=0.745, 95% CI: 0.647-0.858) years were independent protective factors for these subgroup patients. Conclusion. Patients with cT1N0M1 gastric cancer had distinctive clinicopathological characteristics and presented poor prognosis. Knowledge of these differences contributes to guiding clinical evaluation for metastatic gastric cancer patients. More aggressive therapeutic strategy should be highlighted for this subgroup.