PIK3CA and breast cancer: Several FDA-approved cfDNA tests are clinically used in cancer, such as FoundationOne Liquid CDx, which analyzes cfDNA to detect genetic alterations for solid tumors [67]; cobas EGFR mutation test V2 for non-small-cell lung cancer [68]; Guardant360 CDx that detects actionable mutations in lung and breast cancer [69]; Epi proColon 2.0, which looks for methylated Septin9 DNA in colorectal cancer [70]; and Therascreen PIK3CA RGQ PCR, which detects actionable alterations in breast cancer [71].