STS and endometrial cancer: Enzymes involved in estrogen synthesis, such as aromatase, steroid sulfatase (STS), and 17β-hydroxysteroid dehydrogenase type 1 (17βHSD1) [16,17,18,19,20], as well as androgen synthesis enzymes 17βHSD5 and 5α-reductase type 1 (5αRed1) [1,2,21,22,23], are expressed in several malignant tissues, including breast, lung, and endometrial cancers, and biologically active estrogens and androgens, estradiol (E2) and dihydrotestosterone (DHT), are locally synthesized [24,25,26].