Prognostic Value of Mandard Tumor Regression Grade in Rectal Cancer: Association with Histopathological Parameters and Survival Following Neoadjuvant Therapy

In rectal cancer, the evaluation of tumor response after neoadjuvant chemoradiotherapy (nCRT) plays a fundamental role in determining treatment success, prognosis, and decisions regarding adjuvant therapy. The Mandard tumor regression grade (TRG) is a widely used histopathological method for assessing treatment response in this context. This study aimed to investigate the prognostic value of Mandard TRG by analyzing its relationship with histopathological parameters and overall survival. Data from 60 rectal cancer patients who underwent surgery following neoadjuvant therapy between 2020 and 2025 were retrospectively analyzed. TRG was assessed using a three-tier classification (TRG 1: complete response, TRG 2: partial response, TRG 3: no response). Associations between TRG and surgical margin status, lymphovascular invasion, perineural invasion, lymph node status, and survival duration were evaluated. The mortality rate was significantly higher in the TRG 3 group (p=0.008), which also showed significant associations with lymphovascular invasion, perineural invasion, positive surgical margins, and advanced tumor stage. According to Kaplan-Meier analysis, patients in the responder group (TRG 1–2) had a significantly longer average survival time (56.7 months vs. 36.1 months; p=0.010). In multivariate analysis, TRG-based response status was identified as the only variable with borderline statistical significance affecting survival (p=0.057). Mandard TRG is a prognostic tool that reflects not only treatment response but also overall survival in rectal cancer patients following neoadjuvant therapy. Its incorporation into adjuvant treatment decisions and follow-up strategies may contribute significantly to personalized oncologic care.