The potential benefit of adjuvant chemotherapy in locally advanced rectal cancer treated with neoadjuvant chemoradiotherapy is not predicted by tumor regression grade

Introduction Recommended treatment for locally advanced rectal cancer (LARC) is neoadjuvant chemoradiotherapy (NACRT) followed by surgery and total mesorectal excision (TME). The role of adjuvant chemotherapy (ACT) in this regimen is still debated. Assessment of Dworak's tumor regression grade (TRG) after NACRT could potentially select patients who might benefit from ACT. Materials and methods Data for patients who underwent NACRT and TME for LARC between 2007 and 2014 were retrieved from the Bordet Institute database. Overall survival (OS) and disease-free survival (DFS) were calculated for the whole population, according to whether or not they received ACT, and according to TRG. Results We included 74 patients (38 males) with a median age of 62.7 years (33-84 years). AJCC stage cub disease was the most frequent (73%). Pathologic complete response (pCR) was achieved in 13 patients (17.6%). ACT was administered to 42 patients (56.8%). Five-year OS and DFS of patients who received ACT or not were 92 and 84.5% (p = ns), and 79.9 and 84.8% (p = ns), respectively. OS was related to TRG (cut-off value of 3) (p = 0.001). ACT administration was not correlated with improved outcomes in any TRG groups. Conclusion TRG is a prognostic factor for both OS and DFS but does not appear to have a significant benefit for the selection of patients with LARC treated with NACRT who might benefit from the administration of ACT. Prospective randomized trials with larger populations are needed to identify factors that predict which patients may benefit from the administration of ACT.