Tumor DNA is secreted into body fluids that come in direct contact with the tumor site. Body fluids such as urine, plasma or sputum containing DNA from the tumor site is referred to as a liquid biopsy.

Due to its nature liquid biopsies can be obtained in non-invasive or almost non-invasive manner, which makes them a very attractive sample source for molecular diagnostics, see: PMID:29872715.

DNA methylation biomarkers have been shown to be readily detectable in liquid biopsies. Moreover, tests for early cancer detection or relapse monitoring are already in use in clinical disease management.

Methylation-Sensitive High-Resolution Melting (MS-HRM) is a technology that can be utilized for methylation biomarkers detection in liquid biopsies.