Problem of cancer surgery
Doctor Answers (2) on Problem of cancer surgery
2. nearby bone or cartilage or skeletal muscle is involved.
3. some cancer tissue is left out during surgery.
Your surgeon would have checked the tissue histopathology report (should be reported from a centre which sees only cancer patients) to look for all of the abovesaid findings and then probably told you not to worry.
But if any findings are present in your father's report, then he has to receive radiation to his mouth and neck to reduce the high chance of recurrence (coming back) of his cancer.