Metastatic cancer isn't something that goes away. You manage it and live your life with it, but it is always with you. You tame it with treatments, nuke the hell out of it with cobalt-60, and get immune therapies to better fight it yourself. It might even seem to go away, but a doctor would never say you've been completed cured because all it takes is one cell, somewhere, hidden away to return.
Physical addiction is a neurological and psychological illness. You fight it every day, and everyone's fight is different. People manage it, I guess, sometimes and become high performing addicts (I must submit that I might be one).
I suspect that very few people that go rehab are ever "cured" because I don't know if you can cure true physical addiction. It equips people with tools.
Many of these tools are cult-ish and psychological displacement. They replace one addiction (drugs) with another (church). But the underlying pathology remains.
To answer your question -- sometimes it works, sometimes it doesn't. When it doesn't work, we talk about it. When it does work, only a few people find out.