There are several animal studies showing colon cancer tumor regression with the use of cannabinoids, however, there are no human trials and not everything translates from mice to people. Anecdotally there are patients with colon cancer who have improved using cannabis but we don’t know exactly why some patients get better and others don’t. There are many factors involved – not only the cannabinoids, but the terpenes and flavonoids as well. Recent breast cancer studies indicate that cannabis in combination with chemotherapy offers better outcomes than either of then alone. In my opinion, cannabis should be used as an adjunct to conventional therapy, to prevent and treat some of the adverse effects of chemo and/or radiation, and if the tumor responds, consider it an extra added bonus. But I would not depend on cannabis alone to treat any malignancy.