Deficient Mismatch Repair (dMMR) and/or microsatellite instability-high colorectal cancers (CRC) represent 12% of all tumors. dMMR non-metastatic CRC are associated with good prognosis but also with resistance to adjuvant 5FU. dMMR metastatic CRC (mCRC) is found in 5% and its influence on prognosis and chemosensitivity is little known.
This multicenter study included patients with dMMR mCRC treated between 2005 and 2015 in 18 French centers. The Kaplan-Meier method was used to calculate overall survival (OS) and progression-free survival (PFS). Prognostic variables were evaluated in univariate (Log rank test) and multivariate analyses (Cox regression model).
284 patients with dMMR mCRC were included. Lynch syndrome was found in 43% and BRAF mutation in 32%. Median OS was 25.0 months. Peritoneal carcinomatosis (p
This study suggests that dMMR mCRC are associated with poor prognosis with conventional chemotherapy with or without bevacizumab or anti-EGFR. Only surgery of metastasis was associated with better PFS.
Clinical trial identification
Legal entity responsible for the study
D. Tougeron: Consulting or advisory role for Amgen, Sanofi, Celgene. Travel or accommodation from Ipsen, Amgen, Sanofi. J. Taieb: Honoraria: Amgen, Merck, Roche, Baxalta, Celgene, Sanofi, Lilly, Sirtex. T. André: Honoraria: Roche, Bms, Sanofi. All other authors have declared no conflicts of interest.