Laetrile/Amygdalin (PDQ®): Complementary and alternative medicine - Health Professional Information [NCI] - Human / Clinical Studies
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. 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. 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, 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.
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.
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- 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.
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