Prognostic value of tumor regression grade (TRG) after oncological gastrectomy for gastric cancer

Perioperative chemotherapy combined with surgical resection represent the gold standard in the treatment of locally advanced gastric cancer. The Mandard tumor regression score (TRG) is widely used to evaluate pathological response to neoadjuvant treatment. The aim of this study was to assess the prognostic value of TRG in terms of overall survival (OS) and disease-free (DFS).

Retrospective analysis of all consecutive patients who underwent oncological gastrectomy after neoadjuvant chemotherapy from January 2007 to December 2019 for gastric adenocarcinoma was performed. Based on their TRG status they were categorized into two groups: good responders (TRG 1–2) and poor responders (TRG 3–5). Subsequent multivariable analyses were conducted.

Seventy-four patients were included, whereby 15 (20.3%) were TRG 1–2. Neoadjuvant regimens for TRG 1–2 vs. TRG 3–5 were similar: MAGIC (53% vs. 39%), FLOT (40% vs. 36%), FOLFOX (7% vs. 15%, p = 0.462). Histologic types according to Lauren classification for TRG 1–2 vs. TRG 3–5 were: 13% vs. 29% intestinal, 53% vs. 44% diffuse and 34% vs. 27% indeterminate (p = 0.326). TRG 1–2 group exhibited significantly less advanced ypT (46% vs. 10%, p = 0.001) and ypN stages (66% vs. 37%, p = 0.008), alongside a diminished recurrence rate (20% vs. 42%, p = 0.111). The 3-year DFS was significantly better in this group (81% vs. 47%, p = 0.041) whereas the disparity in three-year OS (92% vs. 55%, p = 0.054) did not attain statistical significance.

TRG 1–2 was associated with less advanced ypT and ypN stage and better DFS compared to TRG 3–5 patients, without a significant impact on OS.