Finasteride doesn't block T. This is wrong. Finasteride reduces the conversion of T to DHT (dihydrotestosterone), does nothing to T levels except sometimes actually increase them due to more bioavailable T since less converts to DHT.
Androcur, on the other hand, blocks ALL androgens, T and DHT. One cannot compare to the other. Androcur is a more potent anti-androgen.
Post-op, anti-androgens aren't necessary as you produce minute amounts of T BUT in a few cases, perhaps, finasteride might be needed to prevent hair recession as these people are genetically very sensitive to DHT.