Tumor response evaluation after neoadjuvant chemotherapy in locally advanced gastric adenocarcinoma: a prospective, multi-center cohort study

Background: To verify the prognostic value of the pathologic and radiological tumor response after neoadjuvant chemotherapy in the treatment of locally advanced gastric adenocarcinoma. Methods: A total of 67 patients with locally advanced gastric cancer (clinical >= T2 or nodal disease and without evidence of distant metastases) underwent perioperative chemotherapy (ECF or ECX regimen) from December 2009 through June 2015 in two surgical units. Histopathological and radiological response to chemotherapy were evaluated by using tumor regression grade (TRG) (Becker's criteria) and volume change assessed by CT. Results: Fifty-one (86%) patients completed all chemotherapy scheduled cycles successfully and surgery was curative (R0) in 64 (97%) subjects. The histopathological analysis showed 19 (29%) specimens with TRG1 (less than 10% of vital tumor left) and 25 (37%) patients had partial or complete response (CR) assessed by CT scan. Median disease free survival (DFS) and overall survival (OS) were 25.70 months (range, 14.52-36.80 months) and 36.60 months (range, 24.3-52.9 months), respectively. The median follow up was 27 months (range, 5.00-68.00 months). Radiological response and TRG were found to be a prognostic factor for OS and DFS, while tumor histology was not significantly related to survival. Conclusions: Both radiological response and TRG have been shown as promising survival markers in patients treated with perioperative chemotherapy for locally advanced gastric cancer. Other predictive markers of response to chemotherapy are strongly required.