After years of dismissal, Cannabis now appears as a treatment on the National Cancer Institute Website
Some cannabinoids are psychoactive (acting on the brain and changing mood or consciousness).
By federal law, the use, sale, and possession of Cannabis (marijuana) is illegal in the United States.
What are cannabinoids?
They are also known as phytocannabinoids. 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.
Other possible effects of cannabinoids include:
- Anti-inflammatory activity.
- Blocking cell growth.
- Preventing the growth of blood vessels that supply tumors.
- Antiviral activity.
- Relieving muscle spasms caused by multiple sclerosis.
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 1937, the U.S. Treasury began taxing Cannabis under the Marijuana Tax Act at one dollar per ounce for medicinal use and one hundred dollars per ounce for recreational use.
The American Medical Association (AMA) opposed this regulation of Cannabis and did not want studies of its potential medicinal benefits to be limited.
In 1942, Cannabis was removed from the U.S. Pharmacopoeia because of continuing concerns about its safety.
In 1951, Congress passed the Boggs Act, which included Cannabis with narcotic drugs for the first time.
Under the Controlled Substances Act of 1970, marijuana was classified as a Schedule I drug.
Other Schedule I drugs include heroin, LSD, mescaline, methaqualone, and gamma-hydroxybutyrate (GHB).
Although Cannabis was not believed to have any medicinal use, the U.S. government distributed it to patients on a case-by-case basis under the Compassionate Use Investigational New Drug (IND) program between 1978 and 1992.
In the past 20 years, researchers have studied how cannabinoids act on the brain and 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.
How is Cannabis administered?
Cannabis may be taken by mouth or may be inhaled. When taken by mouth (in baked products or as an herbal tea), the main psychoactive ingredient in Cannabis (delta-9-THC) is processed by the liver, making an additional psychoactive chemical.
When Cannabis is smoked and inhaled, cannabinoids quickly enter the bloodstream.
The additional psychoactive chemical is produced in smaller amounts than when taken by mouth.
Have any preclinical (laboratory or animal) studies been conducted using Cannabis or cannabinoids?
Preclinical studies of cannabinoids have investigated the following activities:
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.
A laboratory study of delta-9-THC in hepatocellular carcinoma (liver cancer) cells showed that it damaged or killed the cancer cells.
A laboratory study of cannabidiol (CBD) in estrogen receptor positive and estrogen receptor negative breast cancer cells showed that it caused cancer cell death while having little effect on normal breast cells.
Studies in mouse models of metastatic breast cancer showed that cannabinoids may lessen the growth, number, and spread of tumors.
A laboratory study of cannabidiol (CBD) in human glioma cells showed that when given along with chemotherapy, CBD may make chemotherapy more effective and increase cancer cell death without harming normal cells.
Studies in mouse models of cancer showed that CBD together with delta-9-THC may make chemotherapy such as temozolomide more effective.
Many animal studies have shown that delta-9-THC and other cannabinoids stimulate appetite and can increase food intake.
Cannabinoids have been studied for anti-inflammatory effects that may play a role in pain relief.
Have any clinical trials (research studies with people) of Cannabis or cannabinoid use by cancer patients been conducted?
Cannabis and cannabinoids have been studied in clinical trials for ways to manage side effects of cancer and cancer therapies, including the following:
Nausea and vomiting
Both dronabinol and nabilone are approved by the Food and Drug Administration (FDA) for the treatment of chemotherapy-related nausea and vomiting in patients who have not responded to standard therapy.
Many clinical trials have shown that both dronabinol and nabilone worked as well as or better than some of the weaker FDA-approved drugs to relieve nausea and vomiting.
Newer drugs given for chemotherapy-related nausea have not been directly compared with Cannabis or cannabinoids in cancer patients.
Inhaled Cannabis: Three small trials have studied inhaled Cannabis for the treatment of chemotherapy-related nausea and vomiting.
Various study methods and chemotherapy agents were used with mixed results. There is not enough information to interpret these findings.
Results showed that delta-9-THC was not as effective in increasing appetite or weight gain in advanced cancer patients compared with standard therapy.
Inhaled Cannabis: There are no published studies of the effect of inhaled Cannabis on cancer patients with loss of appetite.
Studies of healthy people who inhaled Cannabis showed that they consumed more calories, especially high-fat and sweet snacks.
Combining cannabinoids with opioids: In a small study of 21 patients with chronic pain, combining vaporized Cannabis with morphine relieved pain better than morphine alone, while combining vaporized Cannabis with oxycodone did not produce significantly greater pain relief.
These findings should be tested in further studies.
Delta-9-THC taken by mouth: Two small clinical trials of oral delta-9-THC showed that it relieved cancer pain. In the first study, patients had good pain relief as well as relief of nausea and vomiting and better appetite.
Neither dronabinol or nabilone is approved by the FDA for pain management.
Whole Cannabis plant extract medicine: A study of a whole-plant extract of Cannabis that contained specific amounts of cannabinoids, which was sprayed under the tongue, found it was effective in patients with advanced cancer whose pain was not relieved by strong opioids alone.
Patients who received the lower doses of cannabinoid spray showed markedly better pain control and less sleep loss compared with patients who received a placebo.
Results showed that, for some patients, control of their cancer-related pain continued without needing higher doses of spray or higher doses of their other pain medicines.
Anxiety and sleep
Inhaled Cannabis: A small case series found that patients who inhaled marijuana had improved mood, improved sense of well-being, and less anxiety.
Whole Cannabis plant extract spray: A trial of a whole-plant extract of Cannabis that contained specific amounts of cannabinoids, which was sprayed under the tongue, found that patients had improved sleep quality.
Have any side effects or risks been reported from Cannabis and cannabinoids?
Adverse side effects of cannabinoids may include:
- Rapid beating of the heart.
- Low blood pressure.
- Muscle relaxation.
- Bloodshot eyes.
- Slowed digestion and movement of food by the stomach and intestines.
A study of over 5,000 men and women without cancer over a period of 20 years found that smoking tobacco was linked with some loss of lung function but that occasional and low use of cannabis was not linked with loss of lung function.
Larger studies that follow patients over time and laboratory studies of cannabinoid receptors in TGCTs are needed to find if there is a link between Cannabis use and a higher risk of TGCTs.
A review of bladder cancer rates in Cannabis users and non-users was done in over 84,000 men who took part in the California Men’s Health Study.
Over 16 years of follow-up and adjusting for age, race/ethnic group and body mass index (BMI), rates of bladder cancer were found to be 45% lower in Cannabis users than in men who did not report Cannabis use.
Both Cannabis and cannabinoids may be addictive.
Symptoms of withdrawal from cannabinoids may include:
- Trouble sleeping.
- Hot flashes.
- Nausea and cramping (rarely occur).
These symptoms are mild compared to withdrawal from opiates and usually lessen after a few days.
Are Cannabis or cannabinoids approved by the U.S. Food and Drug Administration for use as a cancer treatment in the United States?
The U.S. Food and Drug Administration has not approved Cannabis or cannabinoids for use as a cancer treatment.
Are Cannabis or cannabinoids approved by the U.S. Food and Drug Administration for use as a treatment for cancer-related symptoms or side effects of cancer therapy?
Cannabis is not approved by the U.S. Food and Drug Administration (FDA) for the treatment of any cancer-related symptom or side effect of cancer therapy.
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.