WFDC2 and cancer: Expression of HE4 has been demonstrated in numerous types of normal human tissues, particularly in the epithelium of the respiratory and genitourinary tracts of men and women, and increased HE4 expression has been demonstrated in a range of malignant neoplasms, particularly those of gynecological, pulmonary, and gastrointestinal origin (Galgano et al., 2006; Geng et al., 2015; Ideo et al., 2015).