Abstract 124P
Background
BRAF V600E is identified approximately 5-9% of colorectal cancer (CRC) patients. Non-V600E BRAF mutation is characterized a rare molecular subtype. The clinical characteristics and prognostic impact of non-V600 BRAF mutants are not well defined.
Methods
We recruited 829 patients with CRC from our institution. Tissue samples were molecularly tested. Clinical data was retrospectively reviewed and analyzed using Chi-square and t-test. Overall survival (OS) was compared by log-rank test.
Results
All BRAF mutation was detected in 50 (6%) patients including 24 (3%) patients with non-V600 mutations. Patient characteristics and BRAF testing technique were not significantly different based on BRAF status and it was comparable between BRAF V600E and non-V600 groups. There were significantly more ALL RAS and PIK3CA mutations in non-V600 mutant patients. Patients with non-V600 mutation had median OS of 82 months which was longer than BRAF WT, 66 months, and 31 months of BRAF V600E group, respectively (P=0.067). OS according to treatment with anti-EGFR in metastatic CRC patients was not significantly different in both V600E and non-V600 BRAF mutant groups. Table: 124P
| BRAF-MT (n=50) | |||||||
| BRAF-WT (n=779) | BRAF-MT (n=50) | p-value | V600 (n=26) | non-V600 (n=24) | p-value | ||
| Age | 63 (18 - 93) | 65 (19-85) | 66 (19 - 85) | 65 (24 - 83) | |||
| Sex | |||||||
| Male | 471 (60) | 32 (64) | 0.62 | 15 (58) | 17 (71) | 0.333 | |
| Female | 308 (40) | 18 (36) | 11 (42) | 7 (29) | |||
| Sidedness | |||||||
| Left | 591 (76) | 33 (66) | 0.289 | 12 (70) | 15 (62) | 0.878 | |
| Right | 168 (22) | 15 (30) | 7 (27) | 8 (33) | |||
| non-specify | 20 (3) | 2 (4) | 1 (4) | 1 (4) | |||
| Technique | |||||||
| NGS | 547 (70) | 38 (76) | 0.466 | 18 (69) | 20 (83) | 0.26 | |
| Pyrosequencing | 84 (11) | 6 (12) | 5 (19) | 1 (4) | |||
| PCR | 148 (19) | 6 (12) | 3 (12) | 2 (12) | |||
| All RAS mutation | 418 (54) | 8 (16) | <0.001 | 0 | 8 (33) | 0.001 | |
| PIK3CA mutation | 94 (12) | 9 (18) | 0.218 | 1 (4) | 8 (33) | 0.009 | |
| Recur/Met | (n=575) | (n=35) | (n=19) | (n=16) | |||
| Anti-VEGF | 105 (18) | 7 (20) | 0.796 | 2 (11) | 5 (31) | 0.207 | |
| Anti-EGFR | 162 (28) | 6 (17) | 0.156 | 3 (16) | 3 (19) | 1 |
Conclusions
Non-V600 BRAF mutation may indicate better prognosis. The difference in treatment effect was not demonstrated in patients with BRAF mutation.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Faculty of medicine Ramathibodi Hospital.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.
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