Total Neoadjuvant Therapy Is an Independent Predictor of Complete Pathologic Response in Rectal Cancer Patients

Introduction: Total neoadjuvant therapy (TNT) is a new therapeutic strategy in patients with rectal cancer. We examined the role of TNT, in addition to other preoperative factors, as a predictor for pathologic complete response (pCR). Methods: A retrospective analysis of all rectal cancer patients operated between 2016 and 2021 was conducted. Patients were classified into 2 groups - pCR group and residual tumor group. Patients’ data were reviewed and entered into univariate and multivariate analyses to determine the predictors of the pCR. Results: 172 patients were treated with neoadjuvant therapy and were operated during the study period. 60 patients (34.9%) were treated with TNT while 112 patients (65.1%) were treated with standard chemoradiation before operation. The pCR rate was 25.6% (44 patients) and 128 patients (74.4%) had residual tumor in their pathologic specimens. Comparison of clinical and radiological findings demonstrated no significant differences between the two groups in cT (p=0.46), cN (p=0.52), positive CRM (p=0.72), tumor location (p=0.35), symptomatic presentation (p=0.09), and sphincter involvement (p=0.68).Preoperative TNT was the only significant independent predictor of cPR (OR 2.51, CI95%: 1.15-5.46; p=0.02), while clinical T staging (p=0.83), N stage (p=0.23), CRM status (p=0.57), time interval from NCRT to operation (p=0.45), internal (p=0.71) and external sphincter involvement (p=0.5) were not significant predictive factors of pCR. Conclusion: Rectal cancer patients undergoing TNT before operation have a higher chance of developing complete pathologic response. On the basis of these findings, consideration should be given to TNT rather for traditional preoperative NCRT.