Impact of tumor regression grade on recurrence after preoperative chemoradiation and gastrectomy for gastric cancer

Background and Objectives: It is unknown whether the degree of response to preoperative therapy correlates with locoregional recurrence (LR) or distant recurrence (DR) after resection of gastric cancer. Methods: Patients who underwent resection of gastric adenocarcinoma following chemotherapy and chemoradiation (1995-2015) were reviewed. The tumor regression grade (TRG) was defined by the percentage of viable tumor cells in the specimen (TRG0 = 0%; TRG1 = 1%-2%; TRG2 = 3%-50%; TRG3 ≥ 50%). The relationships among TRG, recurrence-free survival (RFS), LR, and DR were examined. Results: Two hundred forty-seven patients met the inclusion criteria (TRG0, 52 [21%]; TRG1, 49 [20%]; TRG2, 98 [40%]; TRG3, 48 [19%]). LR and DR occurred in 6.1% and 32.0% of patients, respectively. No patient with TRG0 experienced LR. R1 resection (6%-15%) and LR (6%-8%) rates were similar among TRG1-3 patients. R1 resection was associated with LR (hazard ratio [HR], 17.85; P <.001). ypN status (HR, 2.44; P =.004) and linitis plastica (HR, 2.90; P <.001) were associated with DR. TRG was not independently associated with RFS, LR, or DR. Conclusions: TRG0 imparted excellent local control. However, TRG1-3 patients had similar R1 resection rates and therefore similar LR. DR is associated with ypN status and linitis plastica, not TRG.