Prognostic factors in patients with complete response of the tumour (ypT0) after neoadjuvant chemoradiotherapy and radical resection of rectal cancer

Background There are only a few studies on the prognosis of patients with complete response of the tumour (ypT0) after neoadjuvant chemoradiotherapy (NCRT) and radical resection of rectal cancer. The aim of the study was to identify prognostic factors with regard to oncological outcome in ypT0 patients after NCRT and radical resection. Methods All ypT0 patients with rectal cancer after NCRT and radical resection between January 2010 and June 2019 were included. Cox univariate and multivariate regression analyses were used to determine the prognostic factors of these patients. Results Seventy‐six patients with ypT0 rectal cancer were included. In nine patients (11.8%), lymph node metastasis was identified. Age, gender, elevated carcinoembryonic antigen (CEA) and ypN+ were risk factors associated with a worse 5‐year disease‐free survival (DFS) rate in univariate analysis (P = 0.08, 0.14, 0.007 and 0.003, respectively). In multivariate analysis, ypN+ and elevated CEA before NCRT were independent risk factors for worse 5‐year DFS (P = 0.005 and 0.021, respectively). Elevated CEA before NCRT, post‐operative chemotherapy and ypN+ were risk factors associated with worse overall survival in univariate analysis (P = 0.14, 0.002 and 0.17, respectively). However, in multivariate analysis, none of these three factors were independent risk factors for worse overall survival (P = 0.20, 0.34 and 0.06, respectively). Conclusion ypN+ and elevated CEA before NCRT were found to be independent risk factors for an unfavourable DFS in ypT0 patients with complete response of the tumour after neoadjuvant chemoradiotherapy for rectal cancer. Positive lymph nodes and metastatic tumour deposits can still be found in 11.8% of ypT0 patients. Elevated serum carcinoembryonic antigen before neoadjuvant chemoradiotherapy and ypN+ are independent risk factors for disease‐free survival, but none for overall survival in ypT0 patients, and follow‐up and systemic treatment should be strengthened for these patients.