Medical Negligence

Hello Sir/Madam, My Mother had a stage 1 breast cancer for which doctor suggested for breast removal which we had done and after a period 18 months we found that it has spread to liver as well which is termed as Stage 4 Cancer,below are my concerns which i feel doctor has neglected. 1)we have been following with him for every 2 to 3 months from past 18 months during which he didn't suggested a whole scan of the body as the primary character of a cancer cell is it can spread to any part of the body doing a body scan would have helped in diagnosing the issue at an early stage.(i am not sure but doing a whole body scan has been mentioned in the cancer treatment protocol as well). 2)after going through many articles and other patient case studies seems each of them has under gone a basic chemotherapy treatment keeping in mind the unexpected nature of the cell behavior which has not happened in our case. 3)Doctor has not referred us to medical oncology department which should have handled our case on completion of surgery and during our regular followup's as well he didn't suggested us to visit a medical oncology department i am assuming we are victims of medical negligence. please help me in filing case against the doctor i am not expecting any kind of benefits out of this i just wanted to teach a lesson to doctor.