OncologyClinical value of chip-based digital-PCR platform for the detection of circulating DNA in metastatic colorectal cancer

BackgroundThe detection of circulating DNA is considered a promising strategy in cancer patients. Digital PCR has emerged as a sensitive method able to quantify both circulating free and tumour DNA.AimThe aim of this study was to prospectively evaluate the clinical value of a chip-based digital PCR for the detection of circulating DNA.MethodsDigital PCR was used in 34 metastatic colorectal cancer patients to detect and quantify circulating free and tumour DNA based on K-ras mutational status. Clinical outcomes were analyzed according to circulating DNA measurements.ResultsDigital PCR yielded a detection rate of 69% for circulating tumour DNA. The median concentrations of circulating free and tumour DNA were 20 and 6.8 ng/mL, respectively, with significant correlation between both biomarkers (p < 0.001). Median overall survival was 4.8 months in patients with high circulating free DNA (>75% quartile) versus not reached in patients with a low level (<25% quartile) (p = 0.029). Moreover, median overall survival was significantly decreased in patients with detectable circulating tumour DNA compared to those without (respectively 11.8 months versus not reached, p = 0.04).ConclusionsChip-based digital PCR is a simple and non-invasive method allowing the efficient detection of circulating DNA. Our results highlight that levels of these circulating markers may have a potential prognostic value.