Please tell your brother to consider a biopsy, my psa was a 21 ten years ago, got a biopsy, and then had radiation seed therapy, my psa stayed below a 5, for those 10years, of his psa is at a 20, most likely it's prostate cancer. But ghe good news if he gets the radiation therapy, or now you can get hormone therapy to bring his psa numbers down. But doing nothing isn't the way. The psa numbers don't go down by themselves, we must have some kind of intervention, from modern medicine. I hope this helps, good luck on talking to your brother.