Low Maruyama Index Surgery for Gastric Cancer

Abstract

Japanese definitions and treatment guidelines have dominated extent-of-surgery concepts in gastric cancer for over 4 decades, despite the fact that such definitions/guidelines have changed considerably over time, and the fact they have largely failed to improve survival in prospective, randomized clinical trials. To briefly review lessons from previous surgical trials in gastric cancer, and, more specifically, to review data validating the concept of "low Maruyama Index surgery" as a data-driven guide to surgical treatment. Review of results from blinded multivariate analyses of two separate, prospective, randomized clinical trials: (a) the Macdonald Trial of adjuvant postoperative chemo-radiation, Intergroup 0116, conducted in North America; and (b) the Dutch D1-D2 Trial. Blinded univariate and multivariate analysis of both trials establish "Maruyama Index of Unresected Disease" (MI) <5 as a strong independent predictor of better disease-free and overall survival in gastric cancer. Moreover, a strong "dose response" effect for MI versus survival is apparent. In contrast to surgery focused on achievement of a particular Japanese-defined D-level, "low Maruyama Index surgery" is associated with increased disease-free and overall survival. Further, the dose-response effect suggests MI can be used to quantify the adequacy of lymphadenectomy for a given patient. Low MI surgery can be prospectively planned by using the Maruyama Computer Program pre-operatively or intraoperatively.