BRAF Mutation Testing and Metastatic Colorectal Cancer in the Community Setting: Is There an Urgent Need for More Education?

Timothy J. Price, Carol Beeke, Amanda Rose Townsend, Louisa Lo, Roy Amitesh, Robert Padbury, David Roder, Guy Maddern, James Moore, Christos Karapetis

Patients with metastatic colorectal cancer (mCRC) with BRAF mutation (BRAF MT) generally have a poorer prognosis. BRAF MT may also have implications for treatment strategy. Despite this, inclusion of BRAF in routine molecular testing varies. Here we report the frequency of BRAF reporting in the South Australian (SA) mCRC registry reflecting community practice, together with the survival outcomes based on mutation status. The SA population-based mCRC registry was analysed to assess the number of patients where a BRAF MT result was available. The patient characteristics are reported and overall survival was analysed using the Kaplan-Meier method. Of the 3639 patients who have been entered in the registry, only 6.2 % (227) have BRAF MT results available. Of the patients tested, the BRAF MT rate is 12.7 %. The mutation rate was highest in rightsided primary; right colon 23 versus left colon 8.9 % and rectum 7 %. There was no significant difference in median age or male/female proportion. The median overall survival (mOS) for BRAF MT versus wild-type (WT) patients is 14.0 versus 32.9 months (p = 0.003). For patients who have chemotherapy (plus or minus surgery) the mOS is 14.6 months BRAF MT versus 36.1 months (p ≤ 0.001) WT. Liver or lung resection was performed on only 8 % of the BRAF MT group versus 26.5 % of the WT group. Results in a population setting confirm our understanding that BRAF MT is more frequently right sided and of lower frequency in rectal cancer. Survival is lower for patients with mCRC that have BRAF MT, regardless of the therapy. BRAF testing is currently performed infrequently in an Australian setting despite its importance as a significant prognostic factor, and the implications for alternate therapeutic approaches.