I had radiation instead of surgery (I understand that surgery is rare when the cancer has already spread).

Radiation itself isn't automatic for stage 4 — the old-school thinking was that stage 4 was "terminal", so the focus should just be on keeping us comfortable for our remaining years instead of subjecting us to procedures with negative side effects — but since my cancer was oligometastatic (just one metastasis) and my cancer team was up on the latest research and best practices, we decided that radiation to the prostate was worthwhile to help head off future metastases, so I got the full 60 gy (a "curative" rather than "palliative" dose). I have not had chemo, but it might be in my future if the cancer becomes castrate-resistant some day and new metastases pop up.