A proactive approach in the fight against breast cancer is something most cancer patients and doctors believe is the best way to beat this disease ... or at the very least ... the best way to increase your odds of survival. That could be why experts are recommending that women undergoing chemotherapy for breast cancer should undergo an M.R.I. to make sure the treatment is working. Researchers noticed that M.R.I. images can more accurately predict how the tumor is responding to chemotherapy. They also say that an M.R.I. can show whether blood vessels are still forming in the tumor, and whether that tumor is shrinking.