90P - The prognostic impact of RAS and RAF serum mutations in localized colon cancer

Date 10 October 2016
Event ESMO 2016 Congress
Session Poster display
Topics Biomarkers
Presenter Caroline Thomsen
Citation Annals of Oncology (2016) 27 (6): 15-42. 10.1093/annonc/mdw363
Authors C.B. Thomsen, A.L. Appelt, R.F. Andersen, J. Lindebjerg, L.H. Jensen, A. Jakobsen
  • Oncology, Danish Colorectal Cancer Center South, 7100 - Vejle/DK

Abstract

Background

The prognostic impact of RAS/RAF mutations in localised colon cancer needs clarification. Based on analysis of tumour specific DNA this study aimed at elucidating the prognostic impact of mutational status in serum using an extended panel of mutations.

Methods

Stage I-III curatively resected colon adenocarcinoma patients (n = 294) were retrospectively included. Mutations and mismatch repair (MMR) status in tumor were determined at time of operation. The status (categorical) of mutated ctDNA in preoperative serum samples was obtained for patients with tissue mutations. Analyses were performed with droplet digital PCR technology. Hazard ratio (HR) for the association between mutation status and survival was estimated in multivariate analysis taking known prognostic factors into account. Primary endpoints were overall survival (OS) and disease free survival (DFS) and median follow-up was 3.9 and 3.0 years, respectively.

Results

Mutational status in tumor alone (n = 189) had no prognostic impact (p = 0.22). Patients with RAS mutated DNA in both tumor and serum (n = 36) had a significantly worse prognosis, OS (HR= 2.30, 95% CI 1.27-4.15, p = 0.0057) and DFS (HR = 2.18, 95% CI 1.26-3.77, p = 0.0053). BRAF mutated DNA in serum and proficient MMR (pMMR) protein in tumor (n = 14) also reflected significantly worse survival, OS (HR= 3.45, 95%CI 1.52-7.85, p = 0.0032) and DFS (HR= 3.61, 95%CI 1.70-7.67, p = 0.0008). Mutational load had significant prognostic impact as well.

OS HR (95%CI) DFS HR (95%CI)
RAS mutation in serum 2.30 (1.27-4.15) 2.18 (1.26-3.77)
BRAF mutation in serum and pMMR protein in tumor 3.45 (1.52-7.85) 3.61 (1.70-7.67)
Stage I >< Low High >< Mucinous 0.99 (0.43-2.31) 1.41 (0.59-3.38) 0.91 (0.42-1.99) 1.17 (0.50-2.72)
Neural or vascular involvement 1.48 (0.84-2.59) 1.58 (0.94-2.66)
Perforation of the peritoneum 2.10 (1.09-4.04) 1.87 (1.02-3.45)

Conclusions

Mutational status in tumor did not demonstrate any prognostic impact. RAS mutations in serum, and BRAF mutation in serum combined with pMMR in tumor were both strong independent prognostic factors.

Clinical trial identification

S-20140178

Legal entity responsible for the study

Danish Colorectal Cancer Center South

Funding

Danish Colorectal Cancer Center South

Disclosure

C.B. Thomsen: During the last 2 years some travel and accommodation expenses has been paid by Roche. L.H. Jensen: During the last 2 years some travel and accommodation expenses has been paid by Roche, Amgen, Bayer. Honoraria has been given by Astra Zeneca. All other authors have declared no conflicts of interest.