As the number of cancer patients globally increases, a need for reliable biomarkers including circulating tumour DNA from liquid biopsy for diagnosis, prognosis and monitoring of the disease is rising. Currently, mainly tissue samples from biopsy are used, but there are certain limitations: firstly, it is an invasive technique, and secondly, in some cases it is almost impossible to obtain an acceptable tissue sample. This could be changed by using circulating cell-free DNA from liquid biopsy, which also gives the possibility of repeated examination. Here, we focus on the options of isolating circulating cell-free DNA from plasma samples using two isolation techniques: precision manual QIAamp Circulating Nucleic Acid Kit and automatic MagNA Pure Compact (MPC) using Nucleic Acid Isolation Kit I. Manual extraction gave significantly better yields of circulating tumour DNA (P < 0.05). This DNA also had less contaminants (organic compounds or proteins). DNA obtained by both tested methods of isolation is suitable for subsequent molecular genetic methods.

1st Department of Surgery Department of Abdominal Thoracic Surgery and Traumatology 1st Faculty of Medicine Charles University and General University Hospital Prague Czech Republic

Department of Paediatrics and Inherited Metabolic Disorders 1st Faculty of Medicine Charles University and General University Hospital Prague Czech Republic

Institute of Medical Biochemistry and Laboratory Diagnostics 1st Faculty of Medicine Charles University and General University Hospital Prague Czech Republic