What are the benefits and risks of a mastectomy bra?

Maintainyour figure. If you mean mast. Bra and external prothesis -it is to maintain your figure after mastectomy they also make partial implants for filling out partial mastectomy voids. ..... Downside hot, itchy in the summer-colder than you in the winter and expensive needing to be changed yearly but most insurance companies pay for them.
Benefits=simple. The benefits of a mastectomy bra is that it achieves a very simple and straightforward facsimile of the breast with very little risk and no surgery. The risks are few other than aesthetically it may be more obvious in the nude or may be inconvenient with certain activities (swimming, sex, etc.).
Mastectomy. There are no true risks that I know of! It will make you look and feel more normal after your procedure and should not cause a great deal of discomfort.