Questions and Answers About Cannabis from the National Cancer Institute

What is Cannabis? Cannabis, also known as marijuana, is a plant from Central Asia that is grown in many parts of the world today. The Cannabis plant produces a resin containing compounds called cannabinoids.

What are cannabinoids? Cannabinoids are active chemicals in Cannabis that cause drug-like effects throughout the body, including the central nervous system and the immune system. The main active cannabinoid in Cannabis is delta-9-THC. Another active cannabinoid is cannabidiol (CBD), which may relieve pain and lower inflammation without causing the “high” of delta-9-THC.  Cannabinoids may be useful in treating the side effects of cancer and cancer treatment.

What is the history of the medical use of Cannabis? The use of Cannabis for medicinal purposes dates back at least 3,000 years. It came into use in Western medicine in the 19th century and was said to relieve pain, inflammation, spasms, and convulsions.

In the past 20 years, researchers have studied how cannabinoids act on the brain and other parts of the body. Cannabinoid receptors (molecules that bind cannabinoids) have been discovered in brain cells and nerve cells in other parts of the body. The presence of cannabinoid receptors on immune system cells suggests that cannabinoids may have a role in immunity.

If Cannabis is illegal, how do some cancer patients in the United States use it? Though federal law prohibits the use of Cannabis, the map below shows the states and territories that allow its use for certain medical conditions.

Have any preclinical (laboratory or animal) studies been conducted using Cannabis or cannabinoids?  Studies in mice and rats have shown that cannabinoids may inhibit tumor growth by causing cell death, blocking cell growth, and blocking the development of blood vessels needed by tumors to grow. Laboratory and animal studies have shown that cannabinoids may be able to kill cancer cells while protecting normal cells.
Cannabinoid receptors (molecules that bind cannabinoids) have been studied in the brain, spinal cord, and nerve endings throughout the body to understand their roles in pain relief.

Have any clinical trials (research studies with people) of Cannabis or cannabinoid use by cancer patients been conducted?  No clinical trials of Cannabis as a treatment for cancer in humans have been found in the CAM on PubMed database maintained by the National Institutes of Health.

Two cannabinoids (dronabinol and nabilone) are approved by the FDA for the treatment of chemotherapy-related nausea and vomiting in patients who have not responded to standard therapy.

States and Territories That Permit the Medical Use of Cannabis

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