Cancer non-invasive early screening method based on cfDNA sequencing coverage depth characteristic near TSS

The invention discloses a non-invasive cancer early screening method and system based on cfDNA sequencing coverage depth characteristics near TSS. According to the method, sequencing data coverage depth mode difference statistics of tumor-derived cfDNA and healthy individual-derived cfDNA near TSS is carried out in a low-depth whole-gene sequencing mode, an early screening model of cancer is established, and non-invasive early screening of cancer is realized. The method comprises the following steps: defining an upstream and downstream 500bp [-250bp, 250bp] region of TSS as a central region, and an upstream [-2000bp,-1000bp] and a downstream [1000bp, 2000bp] of the TSS as a surrounding region; the NF value of one gene is obtained by dividing the average coverage of the central region by the average coverage of the surrounding region. According to the method, a low-depth whole genome sequencing mode is adopted, the cost is greatly reduced, abnormal changes of fragments earlier than cfDNA mutation can be detect