The management of synchronous metastatic rectal cancer (SMRC) is complex and multimodal, involving chemotherapy, surgery and/or radiotherapy. The aim of this study was firstly to confirm the efficacy of the induction FOLFIRINOX, and secondly to evaluate the different therapeutic strategies and outcomes of patients.

This French study combined data from a prospective FFCD trial and a multicenter cohort. Patients included had SMRC and had undergone induction triplet chemotherapy. Two groups of patients were defined according to the resectability of metastases at baseline: resectable (Res) and unresectable (URes). The primary endpoint was the objective response rate.

146 patients were included in 16 French centers and 65 patients in the FFCD1102 trial. In overall population the median age of patients was 59 years, 86% of tumors were of the lower or middle rectum, 33% were well-differentiated, 53% were RAS mutated and 7% BRAF mutated. Triplet induction was associated with 80% of objective response and 92% of disease control. After the induction phase, 69% and 48% of patients of Res and URes groups underwent rectal surgery, and secondary metastases resection was done in 79% and 39% of patients, respectively. Median overall survival (OS) for Res was 56.3 months (95% CI: 22.54-NA). Median OS for URes who had or not secondary metastases resection were 45.1 months (95% CI: 39.89-NA) and 21.1 months (95% CI 17.31-27.1), respectively. Patients with BRAF mutated tumors were more likely to have unresectable disease, and had worse survivals than the patients with RAS mutated or RAS/BRAF wild-type.

Triplet induction chemotherapy is a treatment of choice in selected patients with SMRC, allowing to adapt the therapeutic strategy to the response and invasiveness of the various sites.

The management of metastatic rectal cancer is essentially based on three main therapeutic approaches: surgery, radiotherapy/chemoradiotherapy and chemotherapy. Induction triplet chemotherapy appears as a good choice for fit and young patients. It allows to adapt the therapeutic strategy to the response and invasiveness of the various sites. In this study dedicated to patients undergoing treatment for rectal cancer with synchronous metastases, FOLFIRINOX-based induction chemotherapy was associated with objective response rate of 77% and disease control rate of 92%. These results are similar with those of the FFCD 1102 trial and confirm the efficacy of induction chemotherapy with FOLFIRINOX with or without targeted therapy in these patients in daily routine practice. Surgery for metastases is a key factor in determining patient's outcome and triplet induction chemotherapy, associated with high response rates, enables a significant percentage of patients to undergo surgery and appears therefore to be a treatment of choice, particularly for patients whose disease is unresectable at baseline.