Nonmetastatic ypt0 rectal cancer after neoadjuvant treatment and total mesorectal excision: Lessons from a retrospective multicentric cohort of 383 patients.

ABSTRACT

BACKGROUND: A better understanding of pathological features and oncological survival in ypT0 rectal cancer after neoadjuvant chemoradiotherapy is required to improve patient selection criteria for rectal-preserving approach by local excision. Our aim was to define risk of lymph node metastasis and oncological outcomes in ypT0 rectal cancer after chemoradiotherapy and total mesorectal excision. METHODS: All consecutive patients who underwent total mesorectal excision for a nonmetastatic rectal adenocarcinoma classified ypT0 after neoadjuvant chemoradiotherapy, with or without locoregional lymph node involvement (ypN+ or ypN-), in 14 French academic centers between 2002 and 2015 were included. Data were collected retrospectively. Overall and disease-free survival were explored. RESULTS: Among the 383 ypT0 patients, 6% were ypN+ (23/283). Before chemoradiotherapy, 86% (327/380) were staged cT3-T4 and 41% (156/378) were staged cN+. The risk of ypN+ did not differ between cT3-T4 and cT1-T2 patients (P = .345) or between cN+ and cN- patients (P = .384). After a median follow-up of 61.1 months, we observed 95% confidence interval (92%-97%) of 5-year overall survival and 93% confidence interval (91%-96%) of 5-year disease-free survival. In Cox multivariate analysis, overall survival was altered by intra-abdominal septic complications (hazard ratio = 2.53, confidence interval [1.11-5.78], P = .028). Regarding disease-free survival, ypN+ status and administration of adjuvant chemotherapy were associated with a reduced disease-free survival (P = .001 for both). cT3/T4 staging and cN+ staging did not modify overall survival (P = .332 and P = .450) nor disease-free survival (P = .862 and P = .124). CONCLUSION: The risk of lymph node metastasis and the oncological survival do not depend on the initial cT or cN staging in cases of ypT0 complete rectal tumor regression.