Is final TNM staging a predictor for survival in locally advanced rectal cancer after preoperative chemoradiation therapy?

Background: Neoadjuvant chemoradiation therapy has improved the local control rate and overall survival in locally advanced rectal cancers. The purpose of this retrospective study is to evaluate the correlation between the final pathologic stage and survival in these patients. Methods: Patients with biopsy-proven rectal carcinoma, pretreatment staging by magnetic resonance imaging such as T3 or T4 tumors, or node-positive disease were treated with preoperative concomitant 5-fluorouracil-based chemotherapy and radiation, followed by radical surgical resection. Clinical outcome with survival, disease-free survival, recurrence rate, and local recurrence rate were compared with each T and N findings using the American Joint Committee on Cancer Tumor-Node-Metastasis (TNM) staging system. Results: A total of 248 patients were enrolled in this study. Overall survival and disease-free survival at 1, 3, and 5 years were 97.1, 92, and 89.9% and 87.5, 71.1, and 69.5%, respectively. Thirty-six patients (14.5%) had a pathologic complete response after neoadjuvant therapy. The recurrence rate was significantly different between the pathologic complete response group and residual group (5.6 vs 31.1%; P = .002). Five-year disease-free survival was significantly better in the complete response group than the residual tumor group (93 vs 66%; P = .0045). There was no statistical difference in survival or locoregional recurrence rate between these two groups. Conclusions: Posttreatment pathologic TNM stage is correlated to disease-free survival and tumor recurrence rate in locally advanced rectal cancer after preoperative chemoradiation. Also, pathologic complete response to neoadjuvant treatment has its oncologic benefit in both overall recurrence and disease-free survival.