BRAF V600E and KRAS mutations were significantly associated with shorter disease-free survival (DFS) and overall survival (OS) in patients with microsatellite-stable tumors but not in patients with microsatellite instability (MSI) tumors. This according to a study of 2,559 patients with stage III colon cancer treated with adjuvant leucovorin, fluorouracil, and oxaliplatin, with or without cetuximab. Researchers found:

• MSI phenotype was detected in 9.9% of patients, KRAS mutations in 33.1%, and BRAF V600E mutations in 9.0%.

• In multivariate analysis, MSI and BRAF V600E mutation were not prognostic, whereas KRAS mutation was significantly associated with shorter DFS (HR=1.55).

• Subgroup analysis showed in patients with microsatellite-stable tumors that both KRAS (HR for DFS=1.64 and HR for OS=1.7) and BRAF V600E mutation (HR for DFS=1.74 and HR for OS=1.84) were independently associated with worse clinical outcomes.

• In patients with MSI tumors, KRAS status was not prognostic, whereas BRAF V600E mutation was associated with significantly longer DFS (HR=0.23) but not OS (HR=0.19).

Citation: Taieb J, Zaanan A, Le Malicot K, et al. Prognostic effect of BRAF and KRAS mutations in patients with stage III colon cancer treated with leucovorin, fluorouracil, and oxaliplatin with or without cetuximab: A post hoc analysis of the PETACC-8 trial. [Published online ahead of print January 14, 2016]. JAMA Oncol. doi:10.1001/jamaoncol.2015.5225.