Clinical and prognostic features of BRAF V600E-mutant resectable colorectal cancer: A single-center retrospective analysis of Chinese patients.

Abstract

e15505 Background: Molecular subtyping provides a fundamental basis for the selection of strategies for colorectal cancer treatment. Unresectable metastatic colorectal cancer (CRC) with BRAF V600E mutation have received great attentions due to the poor prognosis. Nevertheless, clinical characteristics and prognosis of Chinese patients with BRAF V600E-mutant (BM) resectable CRC remain poorly reported. Methods: Patients with BM resectable CRC were included according to the following criteria: 1) Diagnosed with colorectal adenocarcinoma at Zhongshan Hospital Fudan University from June 2015 to December 2018. 2) Underwent surgery for the primary tumor of CRC without any anti-tumor treatment before surgery. 3) With BRAF V600E mutation confirmed by the genetic test of the primary tumor tissue. 4) No other primary malignant tumors or inherited tumor history. 5) Written informed consent was obtained. Clinical information was collected by consulting electronic medical records with the approval of the Ethics Committee of Zhongshan Hospital Fudan University (Approval code: B2021-739). KRAS exon2 mutant (KM) and KRAS/BRAF wildtype (WT) patients were selected in a 1:1 ratio by matching gender, age, location and the year of surgery with the BM group. Overall survival was defined as the time from surgery to death for any reason or last follow-up (September, 2021). Categorical data were assessed by chi-square test. Survival analysis was performed using Kaplan-Meier survival curve with log-rank test, univariate and multivariate Cox regression analyses. Results: A total of 214 patients with BM resectable CRC met the inclusion criteria. Among them, 111 (51.9%) patients were females and 103 (48.1%) were males, 114 (53.3%) patients were younger than age 65 years while 100 (46.7%) were > = 65 years old, 108 (50.5%) patients’ primary lesions sited on the left side and 106 (49.5%) on the right side. Numbers of patients with resectable metastasis and with mismatch-repair- deficient (dMMR) were both 48 (22.4%). 171 KM patients and 165 WT patients were matched with BM patients and the three groups were balanced in gender, age, and location by matching. The BM group had the worst overall survival ( P < 0.001) with significant higher proportions of stage IIĨIV ( P = 0.002) and dMMR patients ( P < 0.001). Survival analysis in subgroups suggested that the inferior prognosis of the BM group was more pronounced in patients with pMMR or Stage IV CRC. Conclusions: BRAF V600E-mutant resectable CRC presented a higher incidence of dMMR but a worse prognosis than KRAS exon2 mutant or KRAS/BRAF wildtype patients.