Tumour regression grading in patients with residual rectal cancer after preoperative chemoradiation

Background and purposeTo explore the utility of tumour regression grading (TRG, the amount of residual tumour cells in relation to extension of fibrosis) after chemoradiation of rectal cancer.Materials and methodsOf 131 patients who received preoperative chemoradiation in the frame of the randomized trial, pathological complete response (pCR, TRG0), good regression (TRG1), moderate regression (TRG2), and poor regression (TRG3) were recorded in 17%, 31%, 31%, and 22% of patients, respectively.ResultsThe rates of ypN-positive category for TRG0, TRG1, TRG2, and TRG3 groups were 5%, 23%, 45%, and 46%, respectively, p = 0.001. When ypT-category and TRG were evaluated by the logistic regression analysis, only ypT-category remained significant for independent prediction of the risk for mesorectal nodal metastases, p = 0.006. The 4-year (median follow-up) disease-free survival (DFS) for TRG0, TRG1, TRG2, and TRG3 groups were 91%, 67%, 54%, and 47%. When patients with persistent disease (TRG1 vs. TRG2 vs. TRG3) were analyzed separately, TRG had no prognostic value for DFS, p = 0.402.ConclusionsTRG in patients with residual cancer had no prognostic value for the incidence of nodal disease and for DFS. Our findings and literature data question the need for the inclusion of TRG assessment into a routine pathological report.