The most enduring legacy of the meteoric rise of laetrile to a place of preeminence among unconventional therapies for cancer during the 1970s may well be sociological and political, rather then medical in nature. Laetrile spawned a popular movement for freedom of choice in health care decisions spanning the ideological spectrum that probably has not been seen in this country since the time of Harry Hoxsey. Though it had been in use for at least 25 years as a therapy for cancer, it is estimated that at any given time during the mid-1970s, 70,000 people were using laetrile as a cancer treatment, for pain control or as a preventive measure.

In the debate over broader philosophical and political issues, the critical question for cancer patients, whether or not laetrile is an effective therapy for cancer, was largely overshadowed, though clearly laetrile has not lived up to the expectations of many of its most ardent advocates.

According to journalist Michael Culbert, D.Sc., founding member of the laetrile advocacy group Committee for Freedom of Choice in Cancer Therapy, Inc.: I decided very early that the issue was neither scientific nor medical but political. And that issue was--is--simple: What right does the state have, or should it have, to intervene in the medical decisions between a patient and his doctor, particularly if that patient is dying of a "terminal" disease for which there is no known, or guaranteed cure?

Ralph Moss, a key figure in the laetrile controversy in the 1970s, has been a leading critic of the cancer orthodoxy, as well as the political and economic forces he believes drive it, since leaving his position as Assistant Director of Public Affairs at Memorial Sloan-Kettering Cancer Center (MSKCC) in 1977. Moss was fired for aligning himself publicly with a group of MSKCC employees who believed the public was being given inaccurate information on the outcome of animal studies of laetrile's effectiveness. Moss provides a detailed account of the laetrile controversy and his experience at MSKCC in his book The Cancer Industry. Moss states the medical issue this way: Laetrilists are not just advocating a single substance but, like the advocates of other unorthodox therapies, are proposing a new kind of treatment for the patient's body and mind.

There is apparently an irreconcilable difference between laetrilists and orthodox doctors in how they understand cancer. Since the time of John Hunter (1728-1793), orthodox physicians have tended to see cancer as a localized disease that, as Hunter said, "only produces local effects." Such a disease would therefore be curable through localized means--for example, removing the growth through surgery. ...Experiments in this century, and particularly in the past thirty years, have suggested that the body has natural immune mechanisms against cancer analogous to those that function in microbial infections. The corollary of this view is that cancer can be controlled by enhancing the body's normal immune functions, which orthodox methods tend to destroy.

The typical "metabolic therapy" often advocated by proponents of laetrile includes megadoses of vitamins A and C, minerals such as selenium, and enzymes, particularly pancreatic enzymes. And, in order to free these enzymes to act upon cancer cells, practitioners often recommend limiting intake of animal protein. Alcohol, coffee, soft drinks and processed foods may also be proscribed. Finally, some form of engagement with the psychological and spiritual aspects of the illness is often encouraged, as well.

"Laetrile" is a term often used interchangeably with "amygdalin" and "vitamin B-17." Amygdalin was first isolated from bitter almonds by two French scientists in 1830. "Laetrile" is a term coined by Ernst T. Krebs, Sr., and Ernst T. Krebs, Jr., in 1953. It is a contraction of laevo-rotary mandelonitrile beta-diglucoside, a purified form of amygdalin that turns polarized light in a left-handed ("laevo") direction. The Krebses believed that this quality was a vital aspect of the substance's effectiveness against cancer. Amygdalin contains two glucose, or sugar, molecules linked to the compound mandelonitrile, whereas laetrile contains one sugar molecule.

"Laetrile" (with a capital "L") usually refers to the Krebses' original product, whose purification process was patented by them; "laetrile" (with a lower case "l") refers to the commercial form of amygdalin which is most likely a mixture of the left and right-turning forms, which the Krebses believed to be much less effective as a therapy for cancer.

In 1970, Krebs, Jr., advanced the theory that cancer is a vitamin deficiency disease that can be prevented by laetrile, which he dubbed vitamin B-17. Critics of his theory charge that this was an attempt to circumvent FDA regulations which apply to medicines but not vitamins, and also that amygdalin does not meet the definition of a vitamin, since it has not been shown to be required to maintain health and no disease has been associated with its absence.

However, according to Culbert: [The cyanide-bearing sugar compounds] are so widespread in nature that Krebs, the earlier McNaughton Foundation (...a research apparatus for the development of laetrile) and the late Dean Burke Ph.D., the peppery biochemist who for years headed the cytochemistry division of the National Cancer Institute, decided that altogether they constituted one or a complex of B vitamins--which they agreed should be the 17th in the order of definition: Vitamin B-17.

They argued that ubiquity in nature of such compounds was a proof, but not the only proof, of their vitamin nature. Their essential non-toxicity and solubility in water are other characteristics, Dean Burke always argued, that added to their B-vitamin status. But the crux of the vitamin argument was whether or not their absence or depletion led to a pathological condition. For the laetrilists, their absence or depletion did indeed lead to a pathological condition: cancer. Not only that, but laetrile and its breakdown products are involved in a host of other metabolic processes.

Laetrile is a glycoside, a family of substances commonly found in plants, including chick peas, lentils, lima beans, cashews, brown rice and millet. Commercially, laetrile is derived from the kernels of the apricot, peach or bitter almond. Glycosides can be split into one or more molecules of sugar and a non-carbohydrate substance in reaction with water, usually facilitated by an enzyme.

Laetrile breaks down in the body into glucose, benzaldehyde and hydrogen cyanide. Cyanide is toxic to both cancerous and non-cancerous cells. Benzaldehyde, which has also been isolated from burdock, one of the constituent herbs in the Hoxsey therapy, has shown anticancer activity in some animal tests.

McCarthy in a 1982 review in Medical Hypotheses classifies benzaldehyde as a potential cytologic cancer therapy which "retards cancer growth by intervening selectively in the disordered control mechanisms responsible for malignant behavior, without producing direct cytotoxicity."

Amygdalin taken orally has been known to be a poison since ancient times, though amygdalin-laden black and brown bitter seeds were described as antitumor agents in the pharmacopeia of ancient China. Egyptian, Greek, Roman and Arabic physicians also used amygdalin to treat tumors.

It was postulated by Ernst Krebs, Sr., that laetrile killed cancer cells selectively through the action of the enzyme beta-glucosidase. According to Krebs' theory, the enzyme splits amygdalin to release cyanide, which kills nearby cells. Krebs asserted that cancer cells are killed selectively because beta-glucosidase is more abundant in cancerous tissues and also because cancer cells are deficient in another enzyme, rhodanese, which promotes rapid breakdown of cyanide.

Krebs' theory concerning the action of laetrile is very controversial and not accepted by most researchers. An anonymous article entitled "The Committee for Freedom of Choice" published in a 1993 issue of CA - A Cancer Journal for Clinicians, an American Cancer Society publication, disputes Krebs' assertions on the basis that animal tissues contain only trace amounts of beta-glucosidase and that rhodanese is present in equal levels in cancerous and non-cancerous tissues.

According to Glenn D. Kittler, the first documented "successful" use of laetrile with cancer was reported in 1951 by Arthur T. Harris, M.D. of Los Angeles. Prior to the 1970s, laetrile was used as a therapy for cancer primarily by Hans Neiper, M.D., in Germany and Ernesto Contreras, M.D., in Mexico. Contreras, who runs the Clinica del Mar in Tijuana, has been treating patients with laetrile since the early 1960s and continues to do so today. Contreras has never published his outcomes with laetrile, but claims modest results. According to Contreras, 35 percent of patients (most of whom have already failed conventional therapy) do not respond to the therapy. Of the remainder, half experience temporary arrest of their cancers. Among the other half are "more definite responses," ranging from slight improvement to disappearance of symptoms. Contreras estimates that perhaps five percent of the patients are "saved."

Some evaluations of laetrile's effectiveness were conducted during this period, as well. Moss describes a 1953 retrospective study of 44 cancer patients by the California Cancer Commission that for many years was the definitive anti-laetrile study. The Commission claimed that laetrile was "completely ineffective" in humans, laboratory animals or in vitro, though the report later came under attack for omitting physician reports of subjective benefit to patients and a discussion of "toxic cellular changes" in cancer cells that were mentioned in the original laboratory studies. Critics also noted that doses of laetrile given patients were very small compared to those considered by practitioners to be therapeutic.

Nevertheless, during the ensuing years, growing numbers of patients used laetrile and some papers did appear supporting its effectiveness. In 1962, John A. Morrone, an attending surgeon at the Jersey City Medical Center, reported "dramatic relief of pain" in ten patients treated with laetrile, as well as indications of tumor regression.

In the 1966 report, Proceedings of the Ninth International Cancer Congress, Rossi cites a ten-year trial in Europe involving 150 patients that found "50 percent of all cases in treatment showed objective improvement" and concluded that laetrile was "an extremely useful chemotherapeutic drug."

Animal studies carried out in several different laboratories under NCI sponsorship in 1957, 1960, 1969 and 1973 showed negative results. Several sources of laetrile were used in a variety of rodent tumor systems, both with and without beta glucosidase. Other investigators testing laetrile alone or with beta glucosidase in animal systems also found no antitumor activity. Laetrile has also been tested alone and in combination with beta glucosidase in nude mice with human breast and colon tumor xenografts. In its summary of the animal research on laetrile in the report Unconventional Cancer Therapies, the Office of Technology Assessment (OTA) reports that no activity was found in any of these tests.

However, Moss describes three animal experiments using laetrile not mentioned in the OTA report that did have positive results. The first was carried out by the SCIND Laboratories in California in preparation for an Investigational New Drug Permit (IND) application being filed by the McNaughton Foundation in 1970. In their second study on carcinoma of rats (Walker 256) with intraperitoneally injected amygdalin, the mean survival time of controls was 23 days, while the mean survival time of the amygdalin-treated group was 38 days, a 70 percent increase. Every amygdalin-treated rat survived longer than every control animal. Moss quotes Dr. Carl Baker, then director of the NCI, as saying in a letter to Congressman Edward Edwards, "The data provided by the McNaughton Foundation certainly indicates some activity in animal tumor systems."

Further, animal studies conducted in Europe also demonstrated some activity. Dr. Paul Reitnauer, Chief Biochemist of the Manfred von Ardenne Institute in Dresden conducted a test in which 20 of 40 H-strain mice were given bitter almonds in addition to their standard diets. Fifteen days after the initiation of the diet, all the mice were inoculated with 1 million Ehrilch ascites cells. The 20 control mice lived an average of 21.9 days following the injection, while the 20 mice receiving the bitter almonds lived an average of 25.8 days, a statistically significant difference.

Finally, Moss reports that Dr. T. Metianu, director of research in pharmacology-toxicology at the Pasteur Institute in Paris conducted a study using an adenocarcinoma model with mice. Ten mice given subcutaneous amygdalin lived an average of 58 days past the time of tumor take, whereas ten controls lived an average of 21 days. A repetition of the experiment resulted in an average 47 day survival for treated mice and 27 day survival for controls.

The early 1970s saw growing numbers of patients seeking out laetrile as a cancer therapy and it was during this time that the laetrile became the focus of a large-scale political movement, as well. In June 1972, John Richardson, M.D., an Albany, California physician whose used laetrile in his rapidly-expanding practice, was arrested for violating state laws intended to curtail its use. Richardson was a member of the conservative John Birch Society, and its membership rallied around the issue. The three trials of Richardson galvanized a national movement for freedom of choice in medical therapies, and the original Committee for Freedom of Choice in Medical Therapy, Inc. ballooned into a nationwide movement in all 50 states with a membership estimated at 20,000 to 50,000 members. In July 1973, Dean Burke, while still working with the NCI, wrote to Congressman Robert A. Roe that laetrile had been successful in NCI directed studies using the Lewis mouse lung cancer model while the agency consistently denied its efficacy.

1975 was a pivotal year in the controversy over laetrile. In that year a U.S. District Court judge barred the FDA from preventing patients from securing their own supplies of laetrile from foreign sources. Later that same year, federal officials conducted a crackdown on the importation of laetrile into this country. Sixteen people, including Robert Bradford, now affiliated with the American Biologics clinic in Tijuana, were arrested or indicted on charges of smuggling laetrile from Mexico. The principles were eventually found guilty in a lengthy trial, though no prison time was meted out.

It was also during this period that the largest series of animal tests with laetrile was carried out by Chester Stock and colleagues at Memorial Sloan-Kettering Cancer Center in New York and Catholic Medical Center of Brooklyn and Queens. One of the investigators, Kanematsu Sugiura, conducted six initial experiments in mice with spontaneous mammary tumors and found that laetrile showed no significant prevention of growth of primary tumors, but did show an inhibition of lung

These tests were followed by a series of five experiments designed to replicate Sugiura's initial work. Two blinded experiments were conducted in which tumor status was assessed in such a way that observers did not know which mice received laetrile and which were controls. This second set of tests did not confirm Sugiura's original findings. The authors concluded that "laetrile was found to possess neither preventive, nor tumor-regressant, nor antimetastatic, nor curative anticancer activity."

One key difference between the two studies was the method of evaluation--Sugiura used visual gross examination plus microscopic slides, the standard approach at the time, while the second study employed a bioassay technique. In the latter, the lungs of the experimental mice were shredded and injected into other mice; if tumors developed at the injection sites, it was an indication that lung metastases were present.

These tests at MSKCC are extensively chronicled in Moss' book, The Cancer Industry. Sugiura was a respected senior researcher at MSKCC and believed, along with some other researchers, that transplantable tumors in mice were not really representative of human cancers. Sugiura was enthusiastic about the potential of laetrile to inhibit metastases, and his initial studies were encouraging.

In his book, Moss, at that time an employee at MSKCC, describes political forces at the esteemed research institution that he believes led the administration, initially receptive to the idea of evaluating laetrile and other unproven therapies, to repudiate Sugiura's promising research and, in Moss' opinion, to issue public statements concerning laetrile research at the institution which were misleading. Moss left his position in public affairs at MSKCC as a result of the controversy and went on the become a prominent proponent of open evaluation of unproven methods. In personal communications with Moss, Sugiura maintained his belief until his death in 1979 that laetrile was effective against cancer in the animal systems he studied: I still think my experimental results on the effect of amygdalin (with high doses) on spontaneous mammary tumors (adenocarcinomas) are correct- stoppage of growth of small tumors temporar[il]y; prevent the development of lung metastases 80 percent against 20 percent in the control group (saline); delayed the development of spontaneous mammary cancers for three to four months.

According to the article in CA - A Cancer Journal for Clinicians, patient records submitted by practitioners were analyzed by committees of the California Medical Association and the California Department of Public Health. Also, the FDA and NCI conducted a joint investigation of 12 case histories submitted by Dr. Ernesto Contreras. In all of these case reviews, it was concluded that no therapeutic effect was demonstrated. But as is often the case in reviews of this kind, pathologic proof of malignancy was missing in many cases and in others patients had received conventional therapy as well.

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