Clinicopathologic features and impact of metastasectomy in patients with BRAF-mutant metastatic colorectal cancer.

Abstract

e15547 Background: BRAF V600E mutation is associated with poor prognosis in patients with metastatic colorectal cancer (mCRC), while the non-V600E mutation mCRC patients showed better prognosis than that of V600E mutation. The clinicopathologic features between V600E and non-V600E mutation has not yet been fully evaluated. And the impact of metastasectomy for patients with BRAF-mutant mCRC was not well-known. Methods: A retrospective study was conducted to evaluate the clinical and pathological characteristics of patients with BRAF-mutant mCRC. Next generation sequencing (22-gene panel) was performed in some of the patients. Survival was also analyzed in the cohort of BRAF V600E and non-V600E mutation with or without metastasectomy. Results: Between December 2014 and August 2020, 116 patients with BRAF-mutant mCRC were enrolled, including 94 patients with BRAF V600E mutation and 22 patients with non-V600E mutation. Significant difference was observed in the prevalence of peritoneal metastasis (69.1% vs. 27.3%, P = 0.001) and lung metastasis (11.7% vs. 36.4%, P = 0.009) between BRAF V600E mutation and non-V600E mutations. In genomic profile, SMAD4 mutation (30.7% vs. 13.7%) showed higher prevalence in patients with BRAF V600E mutation than that of non-V600E mutations, while RAS mutation (18.2% vs. 6.4%) and FBXW7 mutation (13.7% vs 3.1%) had higher incidence in BRAF non-V600E mutations than that of V600E mutation. Patients with BRAF V600E mutation showed a poorer overall survival than those with non-V600E mutations (13.9 vs. 26.8 months, P = 0.038). Totally, 46 patients received metastasectomy after systemic treatment. The median survival for BRAF V600E patients with or without metastasectomy was not reach (42.3+ months) vs. 8.3 months, respectively ( P < 0.001), and for non-V600E patients with or without metastasectomy was not reach (64.2+ months) vs. 23.3 months, respectively (P < 0.001). In multivariate analysis, ECOG performance status (0-1 vs. 2) ( P = 0.001), Staging (IVa-b vs. IVc) ( P = 0.01) and metastasectomy ( P = 0.001) were independent prognostic factors of overall survival. Conclusions: BRAF V600E mutation defines a subgroup of mCRC with worse prognosis. Metastasectomy might improve the survival benefit in carefully selected BRAF-mutant mCRC patients after systemic treatment.