A NIDA animal study suggests that extracts from whole-plant marijuana can shrink a serious type of brain tumor, and research on mice showed that these extracts can enhance the cancer-killing effects of chemotherapy.  

Although marijuana is not approved by the US Food and Drug Administration as medicine, the plant contains several chemicals called cannabinoids which have been studied for their potential healing properties. Such research has led to the FDA’s approval of two medicines containing some of these chemicals in pill form.

"Recent animal studies have shown that marijuana can kill certain cancer cells and reduce the size of others," the NIDA report reads. "Evidence from one animal study suggests that extracts from whole-plant marijuana can shrink one of the most serious types of brain tumors."

"Research in mice showed that these extracts, when used with radiation, increased the cancer-killing effects of the radiation," it concludes

Several states have also passed laws legalizing marijuana for certain medical purposes however the use of it remains prohibited by federal law.