Florent Mouliere and colleagues published an article in Cancer Cell

Using a liquid biopsy test may be used to help find cancer at an early stage. Liquid biopsy (http://www.liquidbiopsycenter.nl), which is the sampling of bio-fluids such as blood or urine, has shown much promise in replacing cumbersome tissue biopsies to detect and classify disease such as cancer.

Originally designed for prenatal testing (NIPT), it has now become possible to detect tiny fragments of tumor-derived DNA in the blood. Current focus has been on detecting cancer-specific mutations to discriminate tumor DNA released from dying cancer cells from DNA released by normal cells. This is not trivial as the amount of normal DNA in the blood greatly outnumbers that of the tumor DNA molecules. In their meta-analysis, CCA Liquid Biopsy Center researchers Van der Pol and Mouliere demonstrate that mutation-based detection is restricted to small parts of the tumor DNA limiting the sensitivity and thus clinical utility of these tests.

With next-generation sequencing (NGS) similar to that used for the standard NIPT, Mouliere discovered that tumor DNA molecules in the blood have defined molecular signatures with information on specificity, size, position and structure. The researchers critically evaluate recent developments and provide a novel framework to increase the sensitivity of a liquid biopsy, and ultimately detect cancer earlier than currently possible when treatments are much more likely to cure patients.
You can find the article here (https://www.cell.com/cancer-cell/fulltext/S1535-6108(19)30386-1)