What is the best natural treatment for colon cancer?

See your doctor: There are no natural treatments for colon cancer which are proven beneficial. Cure rates with surgery (and chemotherapy or radiation as needed) are very good except in advanced disease.

None: Colon cancer does not respond to anything that a naturopath might advocate. You should be in the hands of an oncologist who can direct your course. Do not let a naturopath mislead you into ineffective remedies (like colonic enemas) which will do not good and allow your cancer to spread and be more difficult to treat.