Non-surgical treatments for colon cancer are chemotherapy and radiotherapy. Sometimes it's not possible to remove all the cancer by surgery, so you may need to have additional treatment with chemotherapy and/or radiotherapy. These treatments are given to destroy any remaining cancer cells and prevent it spreading further. Chemotherapy and radiotherapy are also sometimes used to shrink the tumour before surgery or to kill any cancer cells that are left after surgery. Chemotherapy and radiotherapy can both have side-effects.
Attribution: BUPA