Yoga is great and helps you relax and stay fit. I practice it as well as taking Pilates class. Depending on various factors you may have to watch upper body work - such as down dogs, etc. I know that while I was having radiation I got the OK but was told to take it easy on some wierd upper body poses and twist.
Moving your body and making it stronger can only help you get better, it is also a great stress reliever, especially if you end your session with 5-15 min of meditation.