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Home > Wellness > Health Library > Cannabis and Cannabinoids (PDQ®): Complementary and alternative medicine - Patient Information [NCI]
This information is produced and provided by the National Cancer Institute (NCI). The information in this topic may have changed since it was written. For the most current information, contact the National Cancer Institute via the Internet web site at http://cancer.gov or call 1-800-4-CANCER.
Cannabis, also known as marijuana, is a plant from Central Asia that is grown in many parts of the world today. In the United States, it is a controlled substance and has been classified as a Schedule I agent (a drug with increased potential for abuse and no known medical use).
By federal law, possessing Cannabis (marijuana), is illegal in the United States.
Cannabinoids are active chemicals in Cannabis that cause drug-like effects throughout the body, including the central nervous system and the immune system. They are also known as phytocannabinoids. The main active cannabinoid in Cannabis is delta-9-THC. Another active cannabinoid is cannabidiol, 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.
Other possible effects of cannabinoids include:
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. 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.
Though federal law prohibits the use of Cannabis, 17 states and the District of Columbia permit its use for certain medical conditions.
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 (a substance that acts on the brain and changes mood or consciousness).
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.
A growing number of clinical trials are studying a medicine made from a whole-plant extract of Cannabis that contains specific amounts of cannabinoids. This medicine is sprayed under the tongue.
Preclinical studies of cannabinoids have investigated the following activities:
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.
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
Anxiety and sleep
Adverse side effects of cannabinoids may include:
Because cannabis smoke contains many of the same substances as tobacco smoke, there are concerns about how smoked cannabis affects the lungs. 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.
Both Cannabis and cannabinoids may be addictive.
Symptoms of withdrawal from cannabinoids may include:
These symptoms are mild compared to withdrawal from opiates and usually lessen after a few days.
The U.S. Food and Drug Administration has not approved Cannabis for use as a cancer treatment.
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.
Check NCI's list of cancer clinical trials for cancer CAM clinical trials on marijuana, nabilone, dronabinol and nabiximols that are actively enrolling patients.
General information about clinical trials is available from the NCI Web site.
The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.
Editorial changes were made to this summary.
In writing Cancer Information Summaries, PDQ Editorial Boards review current evidence. They do not make recommendations or develop guidelines. Their work is editorially independent of the National Cancer Institute (NCI). This summary on Cannabis and cannabinoids does not represent a policy statement of NCI or NIH. The summary statement represents an independent review of the literature; that review is not influenced by NCI or any other federal agency.
Complementary and alternative medicine (CAM)—also referred to as integrative medicine—includes a broad range of healing philosophies, approaches, and therapies. A therapy is generally called complementary when it is used in addition to conventional treatments; it is often called alternative when it is used instead of conventional treatment. (Conventional treatments are those that are widely accepted and practiced by the mainstream medical community.) Depending on how they are used, some therapies can be considered either complementary or alternative. Complementary and alternative therapies are used in an effort to prevent illness, reduce stress, prevent or reduce side effects and symptoms, or control or cure disease.
Unlike conventional treatments for cancer, complementary and alternative therapies are often not covered by insurance companies. Patients should check with their insurance provider to find out about coverage for complementary and alternative therapies.
Cancer patients considering complementary and alternative therapies should discuss this decision with their doctor, nurse, or pharmacist as they would any therapeutic approach, because some complementary and alternative therapies may interfere with their standard treatment or may be harmful when used with conventional treatment.
It is important that the same rigorous scientific evaluation used to assess conventional approaches be used to evaluate CAM therapies. The National Cancer Institute (NCI) and the National Center for Complementary and Alternative Medicine (NCCAM) are sponsoring a number of clinical trials (research studies) at medical centers to evaluate CAM therapies for cancer.
Conventional approaches to cancer treatment have generally been studied for safety and effectiveness through a rigorous scientific process that includes clinical trials with large numbers of patients. Less is known about the safety and effectiveness of complementary and alternative methods. Few CAM therapies have undergone rigorous evaluation. A small number of CAM therapies originally considered to be purely alternative approaches are finding a place in cancer treatment—not as cures, but as complementary therapies that may help patients feel better and recover faster. One example is acupuncture. According to a panel of experts at a National Institutes of Health (NIH) Consensus Conference in November 1997, acupuncture has been found to be effective in the management of chemotherapy-associated nausea and vomiting and in controlling pain associated with surgery. In contrast, some approaches, such as the use of laetrile, have been studied and found ineffective or potentially harmful.
The NCI Best Case Series Program, which was started in 1991, is one way CAM approaches that are being used in practice are being investigated. The program is overseen by the NCI's Office of Cancer Complementary and Alternative Medicine (OCCAM). Health care professionals who offer alternative cancer therapies submit their patients' medical records and related materials to OCCAM. OCCAM conducts a critical review of the materials and develops follow-up research strategies for approaches deemed to warrant NCI-initiated research.
When considering complementary and alternative therapies, patients should ask their health care provider the following questions:
National Center for Complementary and Alternative Medicine (NCCAM)
The National Center for Complementary and Alternative Medicine (NCCAM) at the National Institutes of Health (NIH) facilitates research and evaluation of complementary and alternative practices, and provides information about a variety of approaches to health professionals and the public.
CAM on PubMed
NCCAM and the NIH National Library of Medicine (NLM) jointly developed CAM on PubMed, a free and easy-to-use search tool for finding CAM-related journal citations. As a subset of the NLM's PubMed bibliographic database, CAM on PubMed features more than 230,000 references and abstracts for CAM-related articles from scientific journals. This database also provides links to the Web sites of over 1,800 journals, allowing users to view full-text articles. (A subscription or other fee may be required to access full-text articles.) CAM on PubMed is available through the NCCAM Web site. It can also be accessed through NLM PubMed bibliographic database by selecting the "Limits" tab and choosing "Complementary Medicine" as a subset.
Office of Cancer Complementary and Alternative Medicine
The NCI Office of Cancer Complementary and Alternative Medicine (OCCAM) coordinates the activities of the NCI in the area of complementary and alternative medicine (CAM). OCCAM supports CAM cancer research and provides information about cancer-related CAM to health providers and the general public via the NCI Web site.
National Cancer Institute (NCI) Cancer Information Service
U.S. residents may call the NCI Cancer Information Service toll free at 1-800-4-CANCER (1-800-422-6237) Monday through Friday from 8:00 am to 8:00 pm. A trained Cancer Information Specialist is available to answer your questions.
Food and Drug Administration
The Food and Drug Administration (FDA) regulates drugs and medical devices to ensure that they are safe and effective.
Federal Trade Commission
The Federal Trade Commission (FTC) enforces consumer protection laws. Publications available from the FTC include:
PDQ is a comprehensive cancer database available on NCI's Web site.
PDQ is the National Cancer Institute's (NCI's) comprehensive cancer information database. Most of the information contained in PDQ is available online at NCI's Web site. PDQ is provided as a service of the NCI. The NCI is part of the National Institutes of Health, the federal government's focal point for biomedical research.
PDQ contains cancer information summaries.
The PDQ database contains summaries of the latest published information on cancer prevention, detection, genetics, treatment, supportive care, and complementary and alternative medicine. Most summaries are available in two versions. The health professional versions provide detailed information written in technical language. The patient versions are written in easy-to-understand, nontechnical language. Both versions provide current and accurate cancer information.
Images in the PDQ summaries are used with permission of the author(s), artist, and/or publisher for use within the PDQ summaries only. Permission to use images outside the context of PDQ information must be obtained from the owner(s) and cannot be granted by the National Cancer Institute. Information about using the illustrations in the PDQ summaries, along with many other cancer-related images, are available in Visuals Online, a collection of over 2,000 scientific images.
The PDQ cancer information summaries are developed by cancer experts and reviewed regularly.
Editorial Boards made up of experts in oncology and related specialties are responsible for writing and maintaining the cancer information summaries. The summaries are reviewed regularly and changes are made as new information becomes available. The date on each summary ("Date Last Modified") indicates the time of the most recent change.
PDQ also contains information on clinical trials.
A clinical trial is a study to answer a scientific question, such as whether one treatment is better than another. Trials are based on past studies and what has been learned in the laboratory. Each trial answers certain scientific questions in order to find new and better ways to help cancer patients. During treatment clinical trials, information is collected about the effects of a new treatment and how well it works. If a clinical trial shows that a new treatment is better than one currently being used, the new treatment may become "standard." Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.
Listings of clinical trials are included in PDQ and are available online at NCI's Web site. Descriptions of the trials are available in health professional and patient versions. Many cancer doctors who take part in clinical trials are also listed in PDQ. For more information, call the Cancer Information Service 1-800-4-CANCER (1-800-422-6237).
Last Revised: 2012-10-03
If you want to know more about cancer and how it is treated, or if you wish to know about clinical trials for your type of cancer, you can call the NCI's Cancer Information Service at 1-800-422-6237, toll free. A trained information specialist can talk with you and answer your questions.
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