HSD17B3 and cancer: Testicular cancer, having the earliest peak age, at age 29, among all cancers studied here, seems to be more complex, as androgens do not seem to be directly involved in testicular cancer development [72], evidenced by the significant downregulation of the androgen receptor (AR) and HSD17B3, an enzyme critical for testosterone biosynthesis in testicular cancer compared to normal testicular tissues (Figure S13A–C).