I have had a number of yoga students over the years that have been through that. It seems to be very helpful, as it is a discipline that is about slowing down and moving in accordance with your abilities and needs… and being present to what those are. It also has that component about self acceptance, of loving the self as it is. And the breath, physical work, and meditation together are good for natural anxieties as well as for the physical work. And it can be done in a way that is helpful for lymphatic flow.
I can see that Pilates as well would have some great benefits. I know people who have done core work as well as yoga, although I am not up on the research in this area as much. I would think the strength work without heavy weights, and strengthening from the center, and learning how to relearn balance after surgery would all be very helpful.