Laetrile has been used as an anticancer treatment in humans worldwide. Reviewed in [1] Although many anecdotal reports and case reports are available, findings from only two clinical trials [2,3] have been published. No controlled clinical trial (a trial including a comparison group that receives no additional treatment, a placebo, or another treatment) of laetrile has ever been conducted.

Case reports and reports of case series have provided little evidence to support laetrile as an anticancer treatment.[4-8] Reviewed in [1] The absence of a uniform documentation of cancer diagnosis, the use of conventional therapies in combination with laetrile, and variations in the dose and duration of laetrile therapy complicate evaluation of the data. In a case series published in 1962,[6] findings from ten patients with various types of metastatic cancer were reported. These patients had been treated with a wide range of doses of intravenous Laetrile (total dose range, 9–133 g). Pain relief (reduction or elimination) was the primary benefit reported. Some objective responses (responses that are measured rather than based on opinion), such as decreased adenopathy (swollen lymph nodes) and decreased tumor size, were noted. Information on prior or concurrent therapy was provided; however, patients were not followed long-term to determine whether the benefits continued after treatment was stopped. Another case series that was published in 1953 included 44 cancer patients and found no evidence of objective response that could be attributed to laetrile.[9] Most patients with reported cancer regression in this series received recent or concurrent radiation therapy or chemotherapy. Thus, it is impossible to determine which treatment produced the positive results.

Benzaldehyde, which is one of laetrile’s breakdown products, has also been tested for anticancer activity in humans. Two clinical series reported a number of responses to benzaldehyde in patients with advanced cancer for whom standard therapy had failed.[10,11] In one series, 19 complete responses and ten partial responses were reported among 57 patients who had received either oral or rectal beta-cyclodextrin benzaldehyde; however, precise response durations were specified for only two of the patients.[10] Another series by the same investigators used 4,6-benzylidene-alpha-D-glucose, which is an intravenous formulation of benzaldehyde.[11] In this series, seven complete responses and 29 partial responses were reported among 65 patients, with response durations ranging from 1.5 to 27 months. No toxicity was associated with either preparation of benzaldehyde, and it was reported that the responses persisted as long as treatment was continued. Almost all of the patients in these two series had been treated previously with chemotherapy or radiation therapy, but the elapsed time before the initiation of benzaldehyde treatment was not disclosed.

In 1978, the National Cancer Institute (NCI) requested case reports from practitioners who believed their patients had benefitted from laetrile treatment.[12] Ninety-three cases were submitted, and 67 were considered evaluable for response. An expert panel concluded that two of the 67 patients had complete responses and that four others had partial responses while using laetrile.[13] On the basis of these six responses, NCI agreed to sponsor phase I and phase II clinical trials.

The phase I study was designed to test the doses, routes of administration, and the schedule of administration judged representative of those used by laetrile practitioners.[3] The study involved six cancer patients. The investigators found that intravenous and oral amygdalin showed minimal toxicity under the conditions evaluated; however, two patients who ate raw almonds while undergoing oral treatment developed symptoms of cyanide poisoning.

The phase II study was conducted in 1982 and was designed to test the types of cancer that might benefit from laetrile treatment.[2] Most patients had breast, colon, or lung cancer. To be eligible for the trial, patients had to be in good general condition (not totally disabled or near death), and they must not have received any other cancer therapy for at least 1 month before treatment with amygdalin. Amygdalin, evaluated for potency and purity by NCI,[14] was administered intravenously for 21 days, followed by oral maintenance therapy, utilizing doses and procedures similar to those evaluated in the phase I study. Vitamins and pancreatic enzymes were also administered as part of a metabolic therapy program that included dietary changes to restrict the use of caffeine, sugar, meats, dairy products, eggs, and alcohol. A small subset of patients received higher-dose amygdalin therapy and higher doses of some vitamins as part of the trial. Patients were followed until there was definite evidence of cancer progression, elevated blood cyanide levels, or severe clinical deterioration. Among 175 evaluable patients, only one patient met the criteria for response. This patient, who had gastric carcinoma with cervical lymph node metastasis, experienced a partial response that was maintained for 10 weeks while on amygdalin therapy. Fifty-four percent of patients had measurable disease progression at the end of the intravenous course of treatment, and all patients had progression 7 months after completing intravenous therapy. Seven percent of patients reported an improvement in performance status (ability to work or to perform routine daily activities) at some time during therapy, and 20 percent claimed symptomatic relief. In most patients, these benefits did not persist. Blood cyanide levels were not elevated after intravenous amygdalin treatment; however, they were elevated after oral therapy.[2]

Variations in commercial preparations of laetrile from Mexico, the primary supplier, have been documented.[14,15] Incorrect product labels have been found, and samples contaminated with bacteria and other substances have been identified.[14,15] When a comparison was made of products manufactured in the United States and Canada, differences in chemical composition were noted, and neither product was effective in killing cultured human cancer cells.[16]

References

1. Lewis JP: Laetrile. West J Med 127 (1): 55-62, 1977.  [PUBMED Abstract]
   
   
2. Moertel CG, Fleming TR, Rubin J, et al.: A clinical trial of amygdalin (Laetrile) in the treatment of human cancer. N Engl J Med 306 (4): 201-6, 1982.  [PUBMED Abstract]
   
   
3. Moertel CG, Ames MM, Kovach JS, et al.: A pharmacologic and toxicological study of amygdalin. JAMA 245 (6): 591-4, 1981.  [PUBMED Abstract]
   
   
4. Navarro MD: The Philippine experience in the early detection and chemotherapy of cancer. St Tomas J Med 25 (3): 125-33, 1970. 
   
   
5. Ross WE: Unconventional cancer therapy. Compr Ther 11 (9): 37-43, 1985.  [PUBMED Abstract]
   
   
6. Navarro MD: Five years experience with laetrile therapy in advanced cancer. Acta Unio Int Contr Cancrum 15(suppl 1): 209-21, 1959. 
   
   
7. Morrone JA: Chemotherapy of inoperable cancer: preliminary report of 10 cases treated with laetrile. Exp Med Surg 20: 299-308, 1962. 
   
   
8. Brown WE, Wood CD, Smith AN: Sodium cyanide as a cancer chemotherapeutic agent: laboratory and clinical studies. Am J Obstet Gynecol 80 (5): 907-18, 1960. 
   
   
9. Cancer Commission of the California Medical Association.: The treatment of cancer with "laetriles". Calif Med 78 (4): 320-26, 1953. 
   
   
10. Kochi M, Takeuchi S, Mizutani T, et al.: Antitumor activity of benzaldehyde. Cancer Treat Rep 64 (1): 21-3, 1980.  [PUBMED Abstract]
    
    
11. Kochi M, Isono N, Niwayama M, et al.: Antitumor activity of a benzaldehyde derivative. Cancer Treat Rep 69 (5): 533-7, 1985.  [PUBMED Abstract]
    
    
12. Newell GR, Ellison NM: Ethics and designs: laetrile trials as an example. Cancer Treat Rep 64 (2-3): 363-5, 1980 Feb-Mar.  [PUBMED Abstract]
    
    
13. Ellison NM, Byar DP, Newell GR: Special report on Laetrile: the NCI Laetrile Review. Results of the National Cancer Institute's retrospective Laetrile analysis. N Engl J Med 299 (10): 549-52, 1978.  [PUBMED Abstract]
    
    
14. Davignon JP, Trissel LA, Kleinman LM: Pharmaceutical assessment of amygdalin (Laetrile) products. Cancer Treat Rep 62 (1): 99-104, 1978.  [PUBMED Abstract]
    
    
15. Davignon JP: Contaminated laetrile: a health hazard. N Engl J Med 297 (24): 1355-6, 1977.  [PUBMED Abstract]
    
    
16. Levi L, French WN, Bickis IJ, et al.: Laetrile: a study of its physicochemical and biochemical properties. Can Med Assoc J 92: 1057-61, 1965. 
    
    

Glossary Terms

Large or swollen lymph glands.

A substance found in the pits of many fruits such as apricots and papayas, and in other foods. It has been tried in some countries as a treatment for cancer, but it has not been shown to work in clinical studies. Amygdalin is not approved for use in the United States. Also called laetrile.

An incomplete description of the medical and treatment history of one or more patients. Anecdotal reports may be published in places other than peer-reviewed, scientific journals.

A large group of single-cell microorganisms. Some cause infections and disease in animals and humans. The singular of bacteria is bacterium.

A colorless oily liquid used as a flavoring agent and to make dyes, perfumes, and pharmaceuticals. Benzaldehyde is chemically related to benzene.

Glandular organ located on the chest. The breast is made up of connective tissue, fat, and breast tissue that contains the glands that can make milk. Also called mammary gland.

A term for diseases in which abnormal cells divide without control and can invade nearby tissues. Cancer cells can also spread to other parts of the body through the blood and lymph systems. There are several main types of cancer. Carcinoma is a cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is a cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is a cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood. Lymphoma and multiple myeloma are cancers that begin in the cells of the immune system. Central nervous system cancers are cancers that begin in the tissues of the brain and spinal cord. Also called malignancy.

A detailed report of the diagnosis, treatment, and follow-up of an individual patient. Case reports also contain some demographic information about the patient (for example, age, gender, ethnic origin).

A group or series of case reports involving patients who were given similar treatment. Reports of case series usually contain detailed information about the individual patients. This includes demographic information (for example, age, gender, ethnic origin) and information on diagnosis, treatment, response to treatment, and follow-up after treatment.

Relating to the neck, or to the neck of any organ or structure. Cervical lymph nodes are located in the neck. Cervical cancer refers to cancer of the uterine cervix, which is the lower, narrow end (the “neck”) of the uterus.

Treatment with drugs that kill cancer cells.

A case series in which the patients receive treatment in a clinic or other medical facility.

A type of research study that tests how well new medical approaches work in people. These studies test new methods of screening, prevention, diagnosis, or treatment of a disease. Also called clinical study.

The longest part of the large intestine, which is a tube-like organ connected to the small intestine at one end and the anus at the other. The colon removes water and some nutrients and electrolytes from partially digested food. The remaining material, solid waste called stool, moves through the colon to the rectum and leaves the body through the anus.

The disappearance of all signs of cancer in response to treatment. This does not always mean the cancer has been cured. Also called complete remission.

A treatment that is given at the same time as another.

A clinical study that includes a comparison (control) group. The comparison group receives a placebo, another treatment, or no treatment at all.

A currently accepted and widely used treatment for a certain type of disease, based on the results of past research. Also called conventional treatment.

The process of identifying a disease, such as cancer, from its signs and symptoms.

The amount of medicine taken, or radiation given, at one time.

Patients whose response to a treatment can be measured because enough information has been collected.

Having to do with the stomach.

A unit of weight in the metric system. One gram is equal to one thousandth of a kilogram and is approximately 30-times less than an ounce.

Into or within a vein. Intravenous usually refers to a way of giving a drug or other substance through a needle or tube inserted into a vein. Also called IV.

A researcher in a clinical trial or clinical study.

A substance found in the pits of many fruits such as apricots and papayas, and in other foods. It has been tried in some countries as a treatment for cancer, but it has not been shown to work in clinical studies. Laetrile is not approved for use in the United States. Also called amygdalin.

Cancer that forms in tissues of the lung, usually in the cells lining air passages. The two main types are small cell lung cancer and non-small cell lung cancer. These types are diagnosed based on how the cells look under a microscope.

A rounded mass of lymphatic tissue that is surrounded by a capsule of connective tissue. Lymph nodes filter lymph (lymphatic fluid), and they store lymphocytes (white blood cells). They are located along lymphatic vessels. Also called lymph gland.

Treatment that is given to help keep cancer from coming back after it has disappeared following the initial therapy. It may include treatment with drugs, vaccines, or antibodies that kill cancer cells, and it may be given for a long time.

Treatment to correct changes in metabolism that can be caused by disease.

Having to do with metastasis, which is the spread of cancer from the primary site (place where it started) to other places in the body.

The National Cancer Institute, part of the National Institutes of Health of the United States Department of Health and Human Services, is the Federal Government's principal agency for cancer research. The National Cancer Institute conducts, coordinates, and funds cancer research, training, health information dissemination, and other programs with respect to the cause, diagnosis, prevention, and treatment of cancer. Access the National Cancer Institute Web site at http://www.cancer.gov. Also called NCI.

A measurable response.

By or having to do with the mouth.

A protein secreted by the pancreas that aids in the digestion of food.

A decrease in the size of a tumor, or in the extent of cancer in the body, in response to treatment. Also called partial remission.

The first step in testing a new treatment in humans. These studies test the best way to give a new treatment (for example, by mouth, intravenous infusion, or injection) and the best dose. The dose is usually increased a little at a time in order to find the highest dose that does not cause harmful side effects. Because little is known about the possible risks and benefits of the treatments being tested, phase I trials usually include only a small number of patients who have not been helped by other treatments.

A study to test whether a new treatment has an anticancer effect (for example, whether it shrinks a tumor or improves blood test results) and whether it works against a certain type of cancer.

An inactive substance or treatment that looks the same as, and is given the same way as, an active drug or treatment being tested. The effects of the active drug or treatment are compared to the effects of the placebo.

In medicine, the course of a disease, such as cancer, as it becomes worse or spreads in the body.

The use of high-energy radiation from x-rays, gamma rays, neutrons, protons, and other sources to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external-beam radiation therapy), or it may come from radioactive material placed in the body near cancer cells (internal radiation therapy). Systemic radiation therapy uses a radioactive substance, such as a radiolabeled monoclonal antibody, that travels in the blood to tissues throughout the body. Also called irradiation and radiotherapy.

By or having to do with the rectum. The rectum is the last several inches of the large intestine closest to the anus.

A decrease in the size of a tumor or in the extent of cancer in the body.

In medicine, treatment that experts agree is appropriate, accepted, and widely used. Health care providers are obligated to provide patients with standard therapy. Also called best practice and standard of care.

Having to do with symptoms, which are signs of a condition or disease.

Treatment.

Having to do with poison or something harmful to the body. Toxic substances usually cause unwanted side effects.

A nutrient that the body needs in small amounts to function and stay healthy. Sources of vitamins are plant and animal food products and dietary supplements. Some vitamins are made in the human body from food products. Vitamins are either fat-soluble (can dissolve in fats and oils) or water-soluble (can dissolve in water). Excess fat-soluble vitamins are stored in the body’s fatty tissue, but excess water-soluble vitamins are removed in the urine. Examples are vitamin A, vitamin C, and vitamin E.