Some find that upon stopping dutasteride/finasteride, even post-op, there can be a rebound effect and some hair loss so it might be needed for life, once started. Also, post-op, despite T levels dropping by 95% in the blood, DHT levels only drop by 50-60% in tissues such as the prostate and for those sensitive to DHT, this may be a problem.
Dutasteride/finasteride can trigger depression/anxiety in a few people, too. It seems quite rare though.