BRAF-mutated colorectal adenocarcinoma

BRAF-mutated MSI colorectal carcinoma

BRAF mutation in colorectal cancer is associated with microsatellite instability (MSI) through its relationship with high-level CpG island methylator phenotype (CIMP) and MLH1 promoter methylation.

In a study, no evidence existed for a differential prognostic role of BRAF mutation by MSI status (P(interaction) > .50). (23878352)

Combined BRAF/MSI status in colorectal cancer is a tumor molecular biomarker for prognosic risk stratification.

Reduced CDX2 and cytokeratin 20 (CK20) expression in colorectal carcinoma with BRAF mutation and high-level microsatellite instability (MSI-H) has been documented.

BRAF-mutated MSS colorectal carcinoma

BRAF-mutated MSS colorectal carcinoma often displays reduced CDX2 and increased CK7 expression. (24908142)

Knowledge of this altered immunophenotype is important as patients with BRAF-mutated MSS colorectal carcinoma often present with metastatic disease.

The altered tumor immunophenotype may lead to the erroneous assumption that origin from the colon/rectum is unlikely.

Open articles

 Microsatellite instability and BRAF mutation testing in colorectal cancer prognostication. Lochhead P, Kuchiba A, Imamura Y, Liao X, Yamauchi M, Nishihara R, Qian ZR, Morikawa T, Shen J, Meyerhardt JA, Fuchs CS, Ogino S. J Natl Cancer Inst. 2013 Aug 7;105(15):1151-6. doi : 10.1093/jnci/djt173
PMID: 23878352 Free

Paywall references

 BRAF-mutated microsatellite stable colorectal carcinoma: an aggressive adenocarcinoma with reduced CDX2 and increased cytokeratin 7 immunohistochemical expression. Landau MS, Kuan SF, Chiosea S, Pai RK. Hum Pathol. 2014 Aug;45(8):1704-12. doi : 10.1016/j.humpath.2014.04.008 PMID: 24908142