TP53, EGFR and PIK3CA gene variations observed as prominent biomarkers in breast and lung cancer by plasma cell-free DNA genomic testing.

•Highly fresh blood samples with at least 15 ml of initial volumes result increase in isolation efficiency.•Isolation rates increase when isolation procedures are conducted in minutes.•There is an inverse ratio between ctDNA degradation and elapsed time.•TP53 gene variations are highly observed on both breast and lung cancer samples.•EGFR and PIK3CA variations are remarkable in lung and breast tumors, respectively.