Molecular aspects of BRAF and HER2 in prognosis of periampullary carcinoma.

Abstract

Background: Biological behaviour of Periampullary cancers (PACS) differs from pancreatic head cancer, and analysis of molecular alteration is needed. BRAF and HER2 are keys members of the RAS/RAF and EGFR pathway, playing roles in prognostic markers and therapeutic targets.

Methods: A study on 89 PACS patients, undergoing Whipple Pancreaticoduodenectomy, PCR-RFLP, and qPCR methods used for SNP and mRNA expression studies. Clinicopathological and survival data collected. Molecular changes were correlated with Clinicopathological parameters. Survival outcomes were assessed by Kaplan Meir Log rank test.

Results: The study revealed that homozygous mutant BRAF V600E was significantly higher in PAC compared to a healthy control (p = 0.0012). Whereas the genotype frequency of HER2 I1655V was similar among PAC and healthy control. The A > G change in HER2 was associated with tumor arising from duodenum (p = 0.004) and showed poor survival outcome (p = 0.001). Upregulation of BRAF and HER2 was found in 43 % of patients with synergistic effect, the median overall survival (OS) being 50.5 ± 13 months. The increased expression of HER2 was higher in early stage (p = 0.04) PAC. The gene expression did not impact the OS, whereas female gender, G3 tumors, T3-T4 depth of tumour, advanced stage, LN metastasis, LVI and PNI were poor predictors of OS.

Conclusions: BRAF V600E SNP was associated with disease susceptibility, and had increased mRNA expression while HER2 I1655V SNP was associated with poor survival outcome in PAC. The increased expression of BRAF and HER2 in early tumors and their co-expression in PAC exhibit cross talk between RAS/RAF and EGFR pathway in PAC.