Prognostic value of pathologic complete response after neoadjuvant therapy in locally advanced rectal cancer: long-term analysis of 566 ypCR patients.

PURPOSE: In the literature, a favorable prognosis was observed for complete pathologic response after preoperative therapy (ypCR) in patients with locally advanced rectal cancer. The aim of this study is to verify whether ypCR predicts a favorable outcome in a large series of patients. METHODS AND MATERIALS: The Gastro-Intestinal Working Group of the Italian Association of Radiation Oncology collected clinical data for 566 patients with ypCR (ypT0N0) after neoadjuvant therapy. Eligibility criteria included locally advanced rectal cancer with no evidence of metastases at the time of diagnosis, evidence of ypCR after preoperative radiotherapy +/- chemotherapy (CT).
RESULTS: Median radiation dose was 50 Gy. A total of 527 patients (93%) received one of 12 different neoadjuvant CT schedules. Sphincter preservation, anteroposterior resection, and endoscopic surgery were performed in 73%, 22%, and 5% of patients, respectively. Adjuvant CT was administered to 22% of patients. Median follow-up was 46.4 months. Locoregional recurrence occurred in 7 patients (1.6%). Distant metastases occurred in 49 patients (8.9%). Overall, 5-year rates of disease-free survival, overall survival, and cancer-specific survival were 85%, 90%, and 94%, respectively. In multivariate analysis, only age and clinical stage statistically correlated with survival outcome. Adjuvant CT was still of borderline significance (worse for adjuvant CT). No relation was found between survival and neoadjuvant CT schedules.
CONCLUSION: A ypCR after neoadjuvant therapy identified a favorable group of patients, even in this large series of 566 patients collected in 61 centers. Locoregional recurrence occurred only in 1.6% patients.