Finasteride is an Alpha-reductase inhibitor, which inhibits the production of dihydrotestosterone (DHT) from testosterone (a hormone involved in prostate enlargement). The medication may stop the prostate from growing further or, in some cases, cause it to shrink. Benefits can include reduction of urinary retention and avoiding the need for surgery. However it is only subsidised for use third line treatment (surgery and other drug therapies need to have failed or be contraindicated). It would not be recommended at this stage for Mr Scott.