Antitumor tests of amygdalin in transplantable animal tumor systems

Amygdalin, quackery or cure?

BACKGROUND

The cyanogenic diglucoside, amygdalin, has gained high popularity among cancer patients together with, or in place of, conventional therapy. Still, evidence based research on amygdalin is sparse and its benefit controversial.

PURPOSE

Since so many cancer patients consume amygdalin, and many clinicians administer it without clear knowledge of its mode of action, current knowledge has been summarized and the pros and cons of its use weighed.

METHODS

A retrospective analysis was conducted for amygdalin relevant reports using the PubMed database with the main search term "Amygdalin" or "laetrile", at times combined with "cancer", "patient", "cyanide" or "toxic". We did not exclude any "unwanted" articles. Additionally, internet sources authorized by governmental or national institutions have also been included.

SECTIONS

Individual chapters summarize pharmacokinetics, preclinical and clinical studies and toxicity.

CONCLUSION

No convincing evidence showing that amygdalin induces rapid, distinct tumor regression in cancer patients, particularly in those with late-stage disease, is apparent. However, there is also no evidence that purified amygdalin, administered in "therapeutic" dosage, causes toxicity. Multiple aspects of amygdalin administration have not yet been adequately explored, making further investigation necessary to evaluate its actual therapeutic potential.

The case against laetrile: the fraudulent cancer remedy

The evidence for the claims that laetrile (amygdalin) can prevent or control cancers has been reviewed. The beta-glucosidase content of cancer tissues is low compared to that of normal liver and small intestine. Cancer tissues contain the enzyme rhodanese in amounts comparable to that of liver and kidney and hence, cannot be attacked selectively by cyanide release through beta-glucosidase action on amygdalin. Amygdalin does not have the properties of a vitamin. Rats have been reared for several generations on diets devoid of cyanogenic glycosides, without developing neoplasms. Experiments with tumor-bearing rodents have demonstrated no curative properties by amygdalin administration. Amygdalin is not as non-toxic as claimed, particularly when ingested orally, and especially when taken with plant material high in beta-glucosidase. The claims for cure and control of cancers in humans have been refuted by distinguished physicians who specialize in the treatment of cancer patients. The writings of laetrile proponents are filled with erroneous and absurd statements. The propaganda for the doctrine of "freedom of choice in cancer treatment" deludes many individuals with treatable cancer to reject proven methods of treatment.

Special report on Laetrile: the NCI Laetrile Review. Results of the National Cancer Institute's retrospective Laetrile analysis

The National Cancer Institute, in response to widespread public interest, undertook a retrospective analysis of Laetrile treatment. Only cases thought to have shown objective benefit from Laetrile were solicited by mail request to 385,000 physicians and 70,000 other health professionals and by direct contact with pro-Laetrile groups. Although it is estimated that at least 70,000 Americans have used Laetrile, only 93 cases were submitted for evaluation. Twenty-six of these Laetrile cases had to be eliminated because of insufficient documentation, and an equal number of conventionally treated cases selected from the institute's files were added to the records to be analyzed. A panel of 12 oncologists, who had no knowledge of the actual treatments given, was then asked to evaluate the results of 160 courses of treatment (68 Laetrile, 68 chemotherapy, 24 "no treatment") in the abstracted records from 93 patients. The panel judged six Laetrile courses to have produced a response (two complete and four partial). These results allow no definite conclusions supporting the anti-cancer activity of Laetrile. The National Cancer Institute will use the data in deciding if further study is needed.