Incidence and prognostic factors in patents (pts) with mutant BRAF (mBRAF) metastatic colorectal cancer (mCRC) in Russia

Abstract

Introduction. mBRAF mCRC has the aggressive phenotype. The incidence of such mutation in Europe and the USA is around 8–14%, in Asian countries – 4–8%. The purpose of this population-based study was to determine the incidence and identifying prognostic factors in pts with mBRAF mCRC in Russia. Materials and methods. A multicenter retrospective analysis of clinical data and treatment results of pts with mBRAF mCRC was performed. The main method for determining mutations was a PCR. The main efficacy endpoint was progression free survival (PFS) at the 1 st line. Multivariate analysis was performed using Cox regression model. Results and discussion. 437 out of 8648 pts (5.17%) with a known mutational status had mBRAF (V600). Clinical data were collected from 131/437 (30%): the right-sided primary tumor – in 58,6%, left-sided – in 19%, rectum – in 21,4%. ORR in pts with mBRAF was 31%, median PFS was 6 months. We didn’t revealed any differences between FOLFOXIRI and doublets (XELOX/FOLFOX or XELIRI/FOLFIRI) in terms of PFS (HR 0.9, 95% CI 0.49–1.52, р = 0.6) and OS (HR 1.5, 95% CI 0.61–4.1, р = 0.35) in pts with mBRAF. Conclusions. The incidence of mBRAF gene in the population of pts with mCRC in the Russia is low and we found a high incidence of localization of the primary tumor in the rectum. We didn’t reveal any differences between the usual duplets and standard regimen for such mutation - FOLFOXIRI in term of 1 st line PFS.

Keywords

• colorectal cancer
• mbraf
• epidemiology
• prognosis
• free progression survival
• overall survival