AR and breast cancer: Furthermore, a 5-ARI reduces the conversion of dihydrotestosterone by antagonizing 5α-reductase and inhibits the proliferation of cancer cells in the bladder by altering the synthesis of certain transcripts (ie, circular RNA) that exacerbate BC.37,38 Concordant experimental evidence around AR-mediated carcinogenesis and tumor progression of BC supports the potential role of a 5-ARI in prevention of BC progression in large populations.