Circulating Dna As A Strong Multimarker Prognostic Tool In Metastatic Colorectal Cancer Patients.

3604 Background: The aim of our study was to evaluate the prognostic role of various circulating cell-free DNA (cfDNA) parameters in metastatic colorectal cancer (mCRC) patients. Methods: We used a novel method, termed Intplex, which determines simultaneously from plasma, total cfDNA concentration, cfDNA fragmentation level, KRAS/BRAF mutational status, and cfDNA mutation load (% of mutant cfDNA). These parameters were tested in a mCRC patient cohort (n=98), which enabled validation of plasma DNA as a liquid biopsy to detect KRAS/BRAF mutations using the STARD criteria . Results: Median overall survival (OS) of the patients of the full cohort was 22 months (IC 95% [16.9-28.1]). Data confirmed BRAF mutational status as an excellent factor of poor prognosis (median OS, 22.9 vs. 3.4 months; relative risk (RR)=8.9, (IC95% [3.1-25.4], Pu003c0.001) compared to KRAS mutational status (RR=1.1, IC 95% [0.7-1.9], P=0.66). OS was statistically different in patient groups with lower total cfDNA concentrations (median=28....