Cannabidiol (CBD) has been found to be a hopeful non-toxic alternative to chemotherapy to breast cancer patients. Tha California Pacific Medical Center Research Institute team has published their reports in Molecular Cancer Therapeutics.
They stressed the fact that CBD lacks the psychoactive properties of Cannabis and as such would not violate any Narcotics regulations. However they mention that the research should not be taken as a license to start smoking Marijuana. It is highly unlikely that one can get the amounts of CBD needed for the anti-cancer effect by smoking Cannabis.