Fifty-five years after Richard Nixon listed cannabis on Schedule I among the most dangerous drugs the Drug Enforcement Agency's List of Controlled Substances (characterized as "... drugs, substances, or chemicals are defined as drugs with no currently accepted medical use and a high potential for abuse.") a federal health agency "...has acknowledged that cannabis extracts may help kill certain cancer cells and reduce the size of others."
In other words, a federal health agency has published its opinion that cannabis does not belong on Schedule I.
As reported in Vice Magazine, in April 2017, National Institute on Drug Abuse (NIDA), which is part of the National Institutes of Health, revised a section on its website titled, "How might cannabinoids be useful as medicine?" to state that, "... Research in mice showed that treatment with purified extracts of THC and CBD, when used with radiation, increased the cancer-killing effects of the radiation."
The (rather long and detailed) page on the NIDA website goes on to describe multiple uses for cannabis, as well as many applications that are currently being tested.