Conditional Survival after Surgical Resection of Gastric Cancer: A Multi-Institutional Analysis of the US Gastric Cancer Collaborative

Survival estimates following surgical resection of gastric adenocarcinoma are traditionally reported as survival from the date of surgery. Conditional survival (CS) estimates, however, may be more clinically relevant by accounting for time already survived. We assessed CS following surgical resection for gastric adenocarcinoma. We analyzed 807 patients who underwent resection for gastric adenocarcinoma from 2000 to 2012 at seven participating institutions in the U.S. Gastric Cancer Collaborative. Cox proportional hazards models were used to evaluate factors associated with overall survival. Three-year CS estimates at "x" year after surgery were calculated as follows: CS3 = S(x+3)/S-(x). Overall 1-, 3-, and 5-year overall survival rates after gastric resection were 42, 34, and 30 %, respectively. Using CS estimates, the probability of surviving an additional 3 years given that the patient had survived at 1, 3, and 5 years were 56, 71, and 82 %, respectively. Patients with higher risk at baseline (i.e., stage III or IV disease, lymphovascular invasion) demonstrated the greatest increase in CS over time. Survival estimates following surgical resection of gastric adenocarcinoma is dynamic; the probability of survival increases with time already survived. Patients with worse prognostic features at the time of surgery had the greatest increases in CS over time. Conditional survival estimates provide important information about the changing probability of survival over time and should be used among patients with resected gastric adenocarcinoma to guide subsequent follow-up strategies