Published online Nov 10, 2018. doi: 10.5306/wjco.v9.i7.133
Peer-review started: July 6, 2018
First decision: August 6, 2018
Revised: August 18, 2018
Accepted: October 24, 2018
Article in press: October 24, 2018
Published online: November 10, 2018
To determine whether the association of rectal adenocarcinoma with a defective-mismatch repair system (dMMR) was associated with a pathological complete response (pCR) to preoperative chemoradiotherapy.
A case-control study was designed with the aim of determining if patients with rectal adenocarcinoma with dMMR had an associated high pCR rate in response to neoadjuvant chemoradiotherapy (nCRT).
Seventy-two cases with pCR were compared against 144 controls without pCR. Across 216 cases, the mean age was 56.8 years, 140 (64.8%) were men, and 63 (29.2%) demonstrated the dMMR system. The pCR was associated with G1 tumors, dMMR, the absence of vascular invasion, and low tumor budding in the pretreatment biopsy. In a multivariant analysis, the factors associated with pCR were dMMR (OR: 2.61; 95%CI: 1.355-5.040, P = 0.004) and a low degree of tumor budding (OR: 2.52; 95%CI: 1.366-4.894, P = 0.025).
We found an independent association between dMMR and a low rate of tumor budding, with a higher rate of pCR, in the basal biopsies of patients with rectal carcinoma subjected to nCRT.
Core tip: Defective Mismatch repair (dMMR) and a low number of buds in the pretreatment biopsy were independently associated with a high rate of the pathological complete response. Tumor budding and MMR status should be considered as tools to be implemented in studies that predict the pathological response to preoperative chemo-radiotherapy in rectal cancer.