We designed a refined and innovative method which simultaneously allows the determination of three parameters: the specific quantification of tumor-derived ccfDNA, the ccfDNA fragmentation index, and SNP (Single Nucleotide Polymorphism) or point mutation detection. In addition to its unprecedented sensitivity and specificity, this qPCR based-method (termed IntPlex®), recently patented by the CNRS, is easy and rapid, and the first multiplexed test for ccfDNA.