Prognostic Value of Tumor Regression Grade in Geriatric Patients with Locally Advanced Gastric Adenocarcinoma

Background and Objectives: Tumor regression grade (TRG) in gastric cancer patients treated with neoadjuvant/perioperative chemotherapy is increasingly recognized as an important indicator of treatment efficacy and long-term prognosis. However, in geriatric patients, data on neoadjuvant therapy and on the relationship between pathological response and survival remain limited. In this study, we investigated the prognostic significance of pathological response, assessed according to Becker's TRG in geriatric patients with locally advanced gastric adenocarcinoma who received neoadjuvant/perioperative chemotherapy and underwent gastrectomy. Materials and Methods: We retrospectively analyzed 82 patients aged ≥65 years with histologically confirmed gastric adenocarcinoma who received neoadjuvant/perioperative chemotherapy followed by curative gastrectomy at a single center between 2017 and 2024. Pathological response was evaluated using the Becker tumor regression grading (TRG) system and classified as good (TRG 1-2) or poor (TRG 3). Clinicopathological features, treatment characteristics, disease-free survival (DFS), and overall survival (OS) were compared between groups. Survival was estimated using the Kaplan-Meier method and compared with the log-rank test. Univariable and multivariable Cox proportional hazards models were used to assess the prognostic impact of TRG and other clinicopathological factors on DFS and OS. Results: The study included 82 geriatric patients, of whom 50 (61.0%) showed a good pathological response (TRG 1-2), while 32 (39.0%) showed a poor pathological response (TRG 3). Poor response was more frequently seen in clinical stage III disease and was accompanied by a higher rate of lymphovascular invasion. Median DFS was 42.4 months in the good response group versus 13.0 months in the poor response group (p < 0.001), and median OS was 47.7 and 15.5 months, respectively (p < 0.001). In multivariable analysis, ECOG performance status (HR 2.697; 95% CI 1.381-5.269; p = 0.004), lymphovascular invasion (HR 4.960; 95% CI 1.545-15.919; p = 0.007), and poor pathological response (HR 2.066; 95% CI 1.055-4.045; p = 0.034) remained independent predictors of DFS. For OS, ECOG performance status (HR 2.719; 95% CI 1.398-5.290; p = 0.003), lymphovascular invasion (HR 4.448; 95% CI 1.400-14.132; p = 0.011), and poor pathological response (HR 2.311; 95% CI 1.161-4.601; p = 0.017) remained independent predictors of OS. Conclusions: Our study suggests that pathological response assessed by the TRG system is a valuable prognostic marker in geriatric gastric adenocarcinoma. Good pathological response was associated with longer DFS and OS, while poor pathological response remained an independent predictor of both shorter DFS and OS.