Abstract 79P
Background
The current literature suggests that the prevalence of BRAF mutations in colorectal cancer (CRC) is around 8.7%. Class I, II, and III the reported prevalence is 6.7 %, 0.5%, and 1.2% respectively. Other pathogenic BRAF mutations were reported in 0.12%. The prognosis of CRC patients with BRAF mutations has been described to be worse than CRC patients with BRAF wild type (WT). It is unclear if this is limited to BRAF class I or applies to classes II and III. Here we have explored the prevalence of BRAF class I, II, and III mutations in a large cohort of patients and their prognostic significance.
Methods
Genomic data were sourced from cBioCancer Genomics Portal. The prevalence of BRAF class I, II, and III were estimated in the metastatic colorectal cancer MSK cohort comprising 1134 patients. The association between BRAF class I, II, and III mutations and median overall survival (mOS) was explored. The log-rank test was used to compare mOS between groups of patients with different types of BRAF mutations.
Results
Among the 1134 patients in this cohort, 119 patients (10.5%) had BRAF mutations. Class I (V600E), class II (K601E, G496A), and class III (G466V, N581S, G496E, N581I, D594G, D594N, G596R) were reported in 74 (6.5%), 7 (0.6%) and 17 (1.5%) patients, respectively. Other BRAF pathogenic alterations (H574Y, A33T, P227Hfs*2, A33T, F294L, Y633C, E501K, Y472S, D594V, L312P, A404Cfs*9, D284Efs*4, R558Q, P162S, T599delinsIP, F583C, R6030O, P403Lfs*8, S602Y, A404Cfs*9, R354* and Q356K) were reported in 21 (1.9%) patients. The mOS in patients with BRAF WT was longer than in patients with BRAF class I mutations (70m vs. 18m; p<0.001). The mOS in patients with class II and III BRAF mutations was longer than in patients with class I BRAF mutations (45m vs. 18m; p=0.011). The mOS in patients with BRAF WT was numerically longer than patients with class II and III BRAF mutations (70m vs 45m; p=0.158).
Conclusions
The prevalence of BRAF class I, II, and III in our cohort of patients with CRC was 6.5%, 0.6% and 1.5%. The mOS of patients with BRAF class I was worse than patients with BRAF WT and class II and II.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.