Abstract: The present application provides a detection system and a detection method of genomic carcinogenesis information based on cell-free DNA, particularly plasma cell-free DNA. The system includes a library construction apparatus, a sequencing apparatus and an information analysis apparatus, the library construction apparatus is configured to convert 5-methylcytosine (5-mC) in the cell-free DNA in a to-be-detected sample into 5-formylcytosine (5-fC) and 5-carboxycytosine (5-caC) and convert non-methylated cytosine (C) into uracil (U) by using enzymes, and the information analysis apparatus is capable of analyzing methylation density of genome, fragment size distribution, fragment 5? end motif and/or chromosome stability. With the adoption of the system and the method, early, sensitive and accurate detection and screening of various cancers can be synchronously implemented.

Abstract: Embodiments of the invention provides methods for determining a methylation score of DNA and determining a ctDNA Fraction (CTDF) value. Additional embodiments are as described herein.