What can I do to get rid of the roundness in the stomach area and the wide waistline and stomach pouch? (Photo)

I had breast cancer about 10 years ago, my doctor took out the muscle from stomach area to create my left breast, but now my stomach has a pouch and my waist line is large for my size , went to a consultant physician to see if I could get something done about it, was told it was stomach fat behind the muscle, so the answer was no , is there really nothing that can be done, or is there something I could do my self to loose this gut and shrink my waist line.