Current cancer biomarkers typically include genetic mutations such as breast cancer susceptibility gene 1/2 (BRCA1/2) in breast cancer,3 protein expression levels such as caveolin-1 in gastrointestinal cancers,4 and circulating tumor cells in hepatocellular carcinoma5 or DNA (ctDNA) in the bloodstream.6 The gene discussed is CAV1; the disease is breast cancer.