Evaluation of commercial kits for isolation and bisulfite conversion of circulating cell-free tumor DNA from blood.

"Declarations Competing interestsGEL, HP and MJ are named on two pending US national applications (US/2019/0221286 and WO/2019/106149) covering the 4Plex control and PoDCall algorithm used in the present study for normalization of DNA methylation ddPCR results. The remaining authors have nothing to disclose. Ethics approval and consent to participateThe study was approved by the Regional Committee for Medical and Health Research Ethics, South-Eastern Norway (Project ID 1.2005.1629 and 2010/1805). Written informed consent was obtained from all patients, and the study was conducted in accordance with the Declaration of Helsinki. Consent for publicationNot applicable. Competing interests GEL, HP and MJ are named on two pending US national applications (US/2019/0221286 and WO/2019/106149) covering the 4Plex control and PoDCall algorithm used in the present study for normalization of DNA methylation ddPCR results. The remaining authors have nothing to disclose."

"Funding Open access funding provided by University of Oslo (incl Oslo University Hospital) This work was supported by the Norwegian Cancer Society, Project Number 216129-2020, and the Norwegian Esophageal Cancer Consortium (NORECa), Project Number 220115-2020."