Among more than fifteen ovarian cancer‐related biomarkers identified to date, the most widely studied include CA‐125, HE4, kallikreins, prostasin (PSN), transthyretin (TTR), transferrin, vascular endothelial growth factor (VEGF), apolipoprotein A‐I (ApoA‐I), and osteopontin (OPN) [42]. The gene discussed is SPP1; the disease is ovarian cancer.