Into the Unknown-exploring a Rare BRAF K601E Mutation in a Rectal Adenocarcinoma

Aim: v-Raf murine sarcoma viral oncogene homolog B (BRAF) gene mutations are broadly divided as BRAF V600E and BRAF non-V600E. These groups exhibit differences in the clinical, histological, molecular and therapeutic mechanisms.

Case Presentation and Discussion: The case described is of a middle aged female with an aggressive rectal adenocarcinoma diagnosed on biopsy and immunohistochemistry. A rare BRAF non-V600E mutation at codon 601, K601E was detected. This mutation has been described in very few cases of colonic adenocarcinoma. The tumor showed extensive local and peritoneal disease with lung metastasis at presentation and progression on the primary line of chemotherapy. The aggressive predisposition of the tumor was contrary to reports suggesting non-V600E tumors to connote a better prognosis.

Conclusion: Active reporting of non-V600E BRAF variants in colorectal adenocarcinoma is essential in order to create a robust database which will help in assessing a biological behavior of these tumors and explore the role of targeted therapy.