Currently, HE4, also known as whey acidic protein four disulfide core 2 (WFDC2), is the only biomarker, other than CA125, which has been approved by the US Food and Drug Administration as a diagnostic marker for ovarian cancer (Hellstrom et al., 2003; Simmons, Baggerly & Bast, 2013). Here, WFDC2 is linked to ovarian cancer.