Cancer Cells do not die, that is how they form Tumors. They grow unchallenged by the fate that cells face when their life cycle normally ends. CBD's attach themselves to Cancer cells and apparently has the ability to turn on the "switch" in the cell that allows it to die, therefore stopping the uncontrolled growth . For persons with other conditions (MS, Lupus, Chronic pain Syndrome, Aids, etc...), this CBD also is what numbs the nerves that are inflamed, thereby reducing pain up to 80 percent. in a large percent of patients.
The whole marijuana plant is best for any patient vs artificial THC pills. The method of ingestion (smoking, vaporizing and eating) all lead to different effects on the body. OD is not possible. if you are using it for a medical use, it would be best to seek a product high in this chemical. A wizened grower will be concerned about CBD levels in the quality weed they distribute, and a reputable medically aware dealer would be able to supply one high in this naturally occurring chemical.
YOUTUBE: CPMCRI's Dr. Sean McAllister - THC and CBD