Cancer FactsComplementary and Alternative Medicine | ||||||
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Date reviewed: 10/10/01
Laetrile/Amygdalin: Questions and AnswersComplementary 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 or nurse, 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.
Laetrile is a compound that has been used as an anticancer treatment in humans worldwide. It is not approved by the Food and Drug Administration for use in the United States. The term “laetrile” is an acronym (laevorotatory and mandelonitrile) used to describe a purified form of the chemical amygdalin. Amygdalin is a plant compound that contains sugar and produces cyanide. Amygdalin is found in the pits of many fruits and raw nuts. It is also found in other plants, such as lima beans, clover, and sorghum. Cyanide is believed to be the active cancer-killing ingredient in laetrile. Although the names laetrile, Laetrile®, and amygdalin are often used interchangeably, they are not the same product. The chemical make-up of Laetrile® patented in the United States is different from the laetrile/amygdalin produced in Mexico. The patented Laetrile® is a semi-synthetic form of amygdalin, while the laetrile/amygdalin manufactured in Mexico is made from crushed apricot pits. The studies discussed in this fact sheet used either Mexican laetrile/amygdalin or Laetrile®. The generic term “laetrile” will be used throughout this fact sheet except in cases where the patented version of Laetrile® is known to have been used in a study.
Amygdalin was first isolated in 1830 and was used as an anticancer agent in Russia as early as 1845. Its first recorded use in the United States as a treatment for cancer was in the 1920s. The early pill form of amygdalin was considered too toxic, and work with the compound was discontinued. In the 1950s, a reportedly nontoxic, semi-synthetic form of amygdalin was developed and patented in the United States as Laetrile®. Laetrile gained popularity in the 1970s as a single anticancer agent and as part of a metabolic therapy program consisting of a special diet, high-dose vitamin supplements, and pancreatic enzymes (a group of proteins that aid in the digestion of food). By 1978, more than 70,000 people in the United States had reportedly been treated with Laetrile®.
Laetrile is administered by mouth (orally) as a pill. It can also be given by injection into a vein (intravenously) or muscle. Laetrile is commonly given intravenously over a period of time and then orally as maintenance therapy (treatment given to help extend the benefit of previous therapy).
Preclinical studies have been conducted with laetrile either alone or in combination with other substances. These studies tested the benefits of laetrile against cancer; the side effects of laetrile treatment; where and how laetrile breaks down in the body; and the way laetrile and its breakdown products leave the body. Laboratory and animal studies have shown little evidence that laetrile is effective against cancer.
Although many anecdotal reports (incomplete descriptions of the medical/treatment history of one or more patients) and case reports (detailed reports of the diagnosis, treatment, and followup of individual patients) are available, they provide little evidence to support laetrile as a treatment for cancer. Findings from only two clinical trials with laetrile have been published. These trials, sponsored by NCI, were conducted in the late 1970s and early 1980s.
The side effects associated with laetrile treatment are like the symptoms of cyanide poisoning. The symptoms include nausea and vomiting, headache, dizziness, bluish discoloration of the skin due to a lack of oxygen in the blood, liver damage, abnormally low blood pressure, droopy upper eyelid, difficulty walking due to damaged nerves, fever, mental confusion, coma, and death. The side effects can be increased by eating raw almonds or crushed fruit pits; eating certain types of fruits and vegetables including celery, peaches, bean sprouts, and carrots; or taking high doses of vitamin C. The side effects of laetrile appear to depend on the method of administration. More severe side effects are experienced when laetrile is given by mouth than when it is given by injection.
The Food and Drug Administration (FDA) has not approved laetrile as a treatment for cancer, although the drug is manufactured and distributed as a cancer treatment in Mexico. To conduct clinical drug research with humans in the United States, researchers must file an Investigational New Drug (IND) application with the FDA. In 1970, an application for an IND to study laetrile was filed by the McNaughton Foundation. This request was approved initially, but was later rejected because animal studies showed that laetrile was not likely to be effective as an anticancer agent. In addition, there were questions about how the proposed study was to be conducted. However, because of several court cases in the 1970s that challenged the FDA’s role in determining which drugs should be available to cancer patients, laetrile was legalized in more than 20 States. In 1980, the U.S. Supreme Court overturned decisions by the lower courts, reaffirming the FDA’s position that drugs must be proven both safe and effective before widespread use in humans. Variations in commercial preparations of laetrile have been documented in Mexico, which is the primary supplier of laetrile. Incorrect product labels have been found, and samples contaminated with bacteria and other substances have been identified.
It is important that the same scientific evaluation which is used to assess conventional approaches be used to evaluate complementary and alternative therapies. A number of medical centers are evaluating complementary and alternative therapies by developing clinical trials to test them. More information about how CAM approaches are evaluated can be found in the National Cancer Institute (NCI) fact sheet Complementary and Alternative Medicine in Cancer Treatment: Questions and Answers. This fact sheet can be accessed at http://cis.nci.nih.gov/fact/9_14.htm on the Internet, or by calling the Cancer Information Service (CIS) at 1–800–422–6237.
Patients and their doctor or nurse can learn about complementary and alternative therapies from the following Government agencies:
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. The information in this fact sheet is not presented as a substitute for informed medical advice. If you have any questions about your individual medical situation, please contact your doctor.
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