What are some good exercises for a cancer survivor postop?

It depends on the CA. This depends on the cancer you had. If you had a muscle cancer, your best exercises are those that strengthen the muscles around that area. If it was a lung cancer, exercises to build up your remaining lung capacity are of help. The best way to find out is to see your doctor for the best rehab. Direction, or, if he has given you one, a good (physical) therapist.