Laetrile is a compound that has been used as an alternative cancer treatment in humans worldwide. However, it is not approved by the Food and Drug Administration for use in the United States-for good reason. Here is what the National Cancer Institute and the National Center for Complementary and Alternative Medicine, a division of the National Institutes of Health, have to say.
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.
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 LaetrileŽ. 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 LaetrileŽ.
However, a growing body of clinical evidence was finding that laetrile had little or no effect as an anti-cancer agent.
In a case series published in 1953, 44 cancer patients did not show any measurable response to treatment with laetrile. Most of the patients who showed some improvement also received radiation therapy or anticancer drugs, so it is impossible to determine which treatment produced the benefit.
In another series of case reports published in 1962, 10 patients with metastatic cancer were treated with a wide range of doses of intravenous LaetrileŽ. Pain relief was the primary reported benefit. Reduced swelling of lymph nodes and decreased tumor size were also reported. However, long-term followup with these patients was not performed, so it is not known how long the benefits lasted after treatment.
Benzaldehyde, which is produced when laetrile is broken down by the body, has also been tested for anticancer activity in humans. In two clinical series (case reports of a number of patients who are treated consecutively in a clinic), patients with advanced cancer who had not responded to standard therapy were treated with benzaldehyde. Some patients experienced a complete response (the disappearance of all signs and symptoms of cancer), while some had a decrease in tumor size. The responses to benzaldehyde lasted as long as the treatment continued. Almost all of the patients had been treated previously with chemotherapy or radiation therapy, but it is not known how soon treatment with benzaldehyde began after the other treatment ended.
In 1978, the National Cancer Institute (NCI) requested case reports from practitioners who believed their patients had benefited from treatment with laetrile. Ninety-three cases were submitted; 67 of these were complete enough to be evaluated. An expert panel concluded that two of the 67 patients had complete responses and four experienced a reduction in tumor size. Based on these six cases, NCI sponsored clinical studies with laetrile.
In 1982, a phase II study with 175 patients looked at which types of cancer might respond to treatment with amygdalin. Most of the patients in this study had breast, colon, or lung cancer. Amygdalin was administered by injection for 21 days, followed by oral maintenance therapy using doses and procedures similar to those evaluated in the phase I study. Vitamins and pancreatic enzymes were also given as part of a metabolic therapy program that also included dietary changes.
In 54 percent of the patients, there was a measurable progression (worsening) of cancer at the end of the treatment. All of the patients showed cancer progression 7 months after completing treatment. Some patients reported an improvement in their ability to work or do other activities, and other patients said their symptoms improved. However, these improvements did not last once treatment ended. On the basis of this study, NCI concluded that no further investigation of laetrile was necessary.
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.
While laetrile is not approved for use in the United States, the drug is manufactured and distributed as a cancer treatment in Mexico. However, variations in commercial preparations of laetrile have been widely documented in that country, which is the primary supplier of laetrile. Incorrect product labels have also been found, and samples contaminated with bacteria and other substances have been identified.
The bottom line is that laetrile may have minimal, if any impact, as an anti-cancer agent. In addition, it may be dangerous to your health.
SOURCES:
National Center for Complementary and Alternative Medicine, National Institutes of Health (http://www.nccam.nih.gov)
National Cancer Institute (http://www.nci.nih.gov)
