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?{115}

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.{116}

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.{117}

"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.{118}

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.{119} 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.{120}

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, DeanBurke 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.{121}

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.{122} Laetrile breaks down in the body into glucose, benzaldehyde and hydrogen cyanide.{123} 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.{124} 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."{125}

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.{126} Egyptian, Greek, Roman and Arabic physicians also used amygdalin to treat tumors.{127}

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.{128}

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.{129}

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.{130} 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."{131}

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.{132}

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.{133}

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."{134}

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.{135} Other investigators testing laetrile alone or with beta glucosidase in animal systems also found no antitumor activity.{136} Laetrile has also been tested alone and in combination with beta glucosidase in nude mice with human breast and colon tumor xenografts.{137} 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.{138} 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."{139}

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.{140}

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.{141}

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.{142} 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.{143}

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.{144}

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 metastases.{145}

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."{146}

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.{147}

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 temporarily; 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.{148}

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.{149}

Critics of mainstream laetrile research have often noted that laetrile is rarely used alone, but more often part of a more comprehensive metabolic regimen. In 1978, Harold Manner, Ph.D., and colleagues conducted the first large scale experiment in animals using laetrile in combination with other supportive therapies. Manner, Chairman of the Department of Biology at Loyola University in Chicago, used a combination of vitamin A, Wobe Mugos enzymes and laetrile with 105 mice with breast tumors. Manner's results were dramatic:

After 6-8 days an ulceration appeared at the tumor site. Within the ulceration was a puslike fluid. An examination of the fluid revealed dead malignant cells...The tumors gradually underwent complete regression in 75 of the experimental animals. This represented 89.3% of the total group. The remaining 9 animals showed partial regression. No attempts were made to determine increase in life span or changes in metastases.{150}

Manner's results were greeted with skepticism by most researchers. Manner was criticized for presenting his results first to a public group- the National Health Federation--rather than to a scientific group, thus intentionally or unintentionally bypassing the peer review process. Manner responded that it would take years for the results to be reviewed and published and that hundreds of thousands of people would die needlessly in the meantime. He was also criticized for not testing laetrile, vitamin A and enzymes separately.{151}

In a follow-up experiment, Manner studied 550 mice with spontaneous mammary tumors using laetrile injected intramuscularly, vitamin A, and digestive enzymes injected into and around the tumor mass. These were tested individually and in various combinations and the animals were observed for signs of tumor regression during a thirty day treatment period. No tumor regressions were observed in animals treated with laetrile alone, vitamin A alone, or both in combination. Tumor regressions were seen in the four treatment groups receiving digestive enzymes, and a few regressions were seen in the control group, as well. Fifty-two percent or more of the tumors regressed in the groups treated with enzymes alone, enzymes and vitamin A, enzymes and laetrile, and laetrile, enzymes and vitamin A in combination. The authors concluded that laetrile alone is "not effective in tumor regression," but that "76 percent of the tumors do completely regress" when all three substances are used in combination. The results were published in the Journal of Manipulative Physiological Therapies in 1978.{152}

Manner's studies are viewed skeptically by most orthodox cancer researchers. For example, the authors of the Office of Technology report state that the observed effect seemed to result from "the immediate proteolytic effect of injecting digestive enzymes directly into tumor masses."{153} Manner countered such criticism by pointing out that no attempt was ever made to replicate his research.

Manner subsequently took over the Cydel Hospital in Tijuana and renamed it the Manner Clinic, which continues to offer the "Manner cocktail" despite Manner's death in 1988.{154}

The OTA also summarized the efforts by the NCI in the mid-1970s to obtain documented evidence of objective responses to laetrile using an approach designed to collect information from individuals or practitioners who felt they had used laetrile successfully in the treatment of cancer. The intention was not to determine rates of success, but rather to collect evidence of antitumor affect. The NCI sent nearly half a million letters to physicians, other health professionals and to pro-laetrile groups asking for documented case histories of patients who had shown objective responses to laetrile, with or without metabolic treatment, with a treatment period of at least 30 days, with a period of at least 30 days prior where no conventional treatment had been used.

Two hundred thirty patients responded with claims of objective response using laetrile. Ninety-three of these gave permission for release of their medical records, and for 26 of these insufficient information was provided for review purposes. The final review was based on the remaining 67 cases. In an effort to avoid bias, twenty-six case histories of patients with similar cancers who received only conventional therapies were added to the laetrile cases. Summaries of the course of the disease without information about the therapy used were prepared for each patient and presented to a panel of 12 oncologists from outside theNCI. A group consensus was reached for each case after a discussion of the individuals reviews.

The panel determined that there were two complete remissions, four partial remissions and nine cases of stable disease. Thirty-five cases were of no value since they did not meet the original criteria for inclusion, and 11 had insufficient data upon which to judge responses. Despite the attempts to blind the panelists regarding laetrile use, a higher than expected proportion answered correctly when asked to guess which patients had used laetrile. Interestingly, the consensus for the six laetrile-treated patients who were determined to have had partial or complete responses and for the three determined to have had increased disease-free survival, was that they had received conventional chemotherapy.

In their discussion of the review, the authors point out that the relatively small number of case submissions and loss of cases due to incomplete information left only a small number of evaluatable cases. Further:

The patients treated with Laetrile were almost always given concomitant metabolic therapy...as well as general supportive-care measures such as improved diet, psychologic support and the unmeasurable ingredient of hope. This fact makes it difficult to attribute any tumor response to Laetrile alone.{155}

Following this case review, the NCI sponsored phase I and II clinical trials, which were carried out at the Mayo Clinic. The phase I study gathered information about dosage and toxicity{156} in preparation for the phase II study.

One hundred seventy-eight patients with advanced cancers were treated with amygdalin according to a regimen designed to resemble "current laetrile practice," which included a special diet and vitamin supplements. A subgroup of 14 patients with colorectal cancer was given a high-dose regimen of amygdalin and supplements resembling high-dose regimens used by some metabolic practitioners.

All patients had disease for which no conventional therapy was available, though none were bedridden and all could eat normally. About a third of the patients had had no chemotherapy whatsoever, significant because of the claims of many practitioners that metabolic therapies are more effective in patients whose immune systems have not been damaged by chemotherapy.

The amygdalin, prepared from apricot pits by the NCI, was administered intravenously for 21 days, followed by continuous oral administration which was terminated with progression of the disease or severe clinical deterioration. Three patients were taken off the regimen because of high blood levels of cyanide.

One of the 175 evaluable patients demonstrated a partial response (at least a 50 percent decrease in the size of the lesion); this response was transient, however. By the end of the three-week course of intravenous amygdalin, more than half of the patients demonstrated measurable disease progression. By seven months, all patients had progressive disease. Median survival for the entire group was 4.8 months, a result similar to that of the 14 high-dose patients. The researchers found little evidence of symptom relief.

Toxicities were generally mild when patients adhered to treatment schedules.

The authors concluded that the survival times of the patients appeared to be consistent with survival times of patients "receiving inactive treatment or no treatment."{157} The OTA report notes that this comparison was not entirely valid, since the trial did not include a randomized control group and was not designed to determine if amygdalin caused moderate increases in lifespan or improvements in well-being or pain control.{158}

Laetrile supporters predictably criticized the study, claiming the material used was not laetrile but a "degraded product."{159} The OTA Report counters that the laetrile used was prepared according to one of several popular formulations in use at the time and that the regimen did correspond to current laetrile practice.{160} American Biologics, then a California company with ties to the Committee for Freedom of Choice in Cancer Therapy, had offered to provide free laetrile for the study and when the government refused the offer, the Committee unsuccessfully tried to block the trial, believing the test substance was not pure amygdalin, but a form that would not release cyanide.{161} According to Culbert:

The "laetrile clinical trial"...wound up being in essence a US government sponsored test of an uncertain laetrile product whose application was in the hands of doctors and scientists known to be or assumed to be hostile to laetrile, whose patients were anonymous, and the test results of which, being coded, could not be individually released or cross-checked. Worse, the patients accepted for entry into the program were variously described as "terminal" or beyond hope of cure by conventional means, yet not at the "final stage."

The government [released] data on the test before the trial results were published as a kind of slide presentation...A Committee observer at the event was able to photograph a slide which showed that a significant number of test patients had remained "stable" while on the injectable part of a program whose oral protocol, we had every reason to believe, was not strongly adhered to (and parts of which, as in suggested vitamin A levels) seemed not to have been followed at all.{162}

The results of the trial published in the New England Journal of Medicine showed laetrile to be ineffective as a cancer treatment, but Culbert and other laetrile advocates believed the trial raised more questions than it answered:

[D]epending on how the numbers were read, either a small majority or a large plurality of patients remained "stable" while on the injectable part of the program, and only advanced into further disease after the 21 days of injections ceased. It later surfaced "anecdotally" that at least one patient was urged not to continue on the program (claiming he had "done too well"). As a corollary, a preliminary test found amygdalin not to be toxic, at least in the ranges suggested for therapeutic use.{163}

And, according to Richard Walters, Dr. James Cason of the University of California, Berkeley, analyzed the compound used in the Mayo Clinic study using infrared spectrophotometry and determined that it did not contain amygdalin at all.{164}

Dr. Moertel and vitamin C trials at the Mayo Clinic

And in a charge often leveled at efforts to evaluate alternative therapies, opponents of the trial pointed out that 66 percent of the patients had received chemotherapy which they believed had severely damaged their immune systems and compromised their ability to respond to laetrile.

The potential toxicity of laetrile has consistently been cited as a serious issue by those in favor of regulation. CA - Cancer Journal for Clinicians cites several case reports describing serious or lethal cyanide toxicity from laetrile ingestion, some resulting from ingestion of laetrile by children and others in adults taking oral laetrile at the prescribed dose levels. The article asserts that cyanide toxicity is a risk only with oral ingestion of laetrile, since it is beta-glucosidase made by bacteria in the intestine decomposes amygdalin into cyanide; with intravenous laetrile, the standard treatment method, most is excreted in the urine without releasing cyanide, and so can have no therapeutic effect.{165}

And according to a toxicity study by E.S. Schmidt published in the Journal of the American Medical Association, the danger of laetrile toxicity is enhanced if foods containing the enzyme beta-glucosidase are eaten along with oral laetrile, since the release of cyanide into the body is accelerated. Raw almonds and other nuts, bean and alfalfa sprouts, peaches, lettuce, celery and mushrooms are all sources of beta glucosidase.{166} Common adverse effects found in the Mayo Clinic study of laetrile included nausea, headaches, vomiting and dizziness.{167}

But Moss points out that the two or three documented deaths ascribed to accidental overdoses of laetrile occurred at a time when 50,000 to 100,000 patients were ingesting over one million grams of laetrile per month.{168} Further, according to Moss, there are no case reports of any deaths or serious injuries resulting from laetrile injections.{169}

Culbert also counters that reports of laetrile toxicity were deliberately exaggerated by opponents. He argues that virtually no laetrile-using physicians prescribed oral laetrile above the dose presumed useful therapeutically, 1.5 grams per day. Further, he argues that intravenous laetrile is considered non-toxic at levels far exceeding those normally prescribed.{170}

Culbert cites a study in Ohio showing toxicity in test animals when up to 1.3 grams per kilogram of body weight were given to monkeys and 6.4 grams per kilogram of body weight given to dogs. Extrapolated to humans, these are levels from five to 300 times the normal oral dose.{171}

He also criticizes a an often-quoted study at University of California Davis in 1978 demonstrating that consumption of certain vegetables with along with oral laetrile could be lethal, and that the often-recommended "laetrile diet" was dangerous. The dogs, he says, were starved, drugged to prevent vomiting, and fed (via a gastric tube) a mash of sweet almonds with amygdalin at a temperature that allowed enzymes in the almonds to "hydrolyze" the amygdalin, causing cyanide release and toxicity in several dogs. Culbert argues the methodology of this and other toxicity tests had little to do with the way patients consume laetrile.{172}

Laetrile opponents also have pointed to the prevalence of impure and potentially dangerous laetrile products, as well as those sold as laetrile which were in fact not laetrile at all. But Culbert and others have countered that these were the outcome of a situation where existing demand was being met by unscrupulous vendors because legal avenues of obtaining the pure product were closed.

Though it continues to be used at several clinics in Mexico and by practitioners in the states where it is legal, in the minds of many, the Mayo Clinic trial was the final word on laetrile. But for laetrile advocates, the scientific questions largely still unresolved, and there remains what seems to some to be abundant anecdotal evidence for the effectiveness of laetrile. According to Culbert:

There were too many doctors stepping forward with case histories...too many dissident scientists claiming there was some merit in the notion of anti-cancer efficacy from glycosidic compounds, and far, far too many "anecdotes" from patients treated in Mexico or even within the USA to be able to claim the apricot kernel extract was totally without value...

[N]otable failures of laetrile therapy got plenty of press attention, particularly if the failures came from the growing caseloads of Drs. Contreras and Richardson. Such negatives were indeed reported in gruesome detail--yet it was only an occasional journalist who dared contrast failures on vincristine, 5 FU, adriamycin, radiation and surgery, since somehow a failure on an orthodox modality was somehow less a failure than one on unorthodox therapy.{173}

In the political effort that had been spearheaded by the Committee for Freedom of Choice in Cancer Therapies, between 1976 and 1981, bills decriminalizing laetrile or legalizing it outright were approved in 24 states. Bills passed twice in New York, but were vetoed each time. Such laws remain in 20 states.{174} According to Culbert:

The Committee stuck to a single sweeping principle--that the issue was not so much freedom for laetrile as it was freedom of informed consent in cancer therapy in general, for physician and patient...One observer after another joined the conceptual battle and usually remained clear on the separation of the issues of freedom of choice in medicine vs. the efficacy of laetrile: by what stroke of logic or presumed vested interest does the state have the right to intervene in life-and-death decisions between a physician and a patient, particularly when the patient is said to be "terminal," as with cancer?{175}

Today, it is illegal to use Laetrile in states that do not have laws specifically allowing it. In 1977, a U.S. District Court judge ruled that the FDA had acted illegally in seizing shipments of Laetrile, and he enjoined the FDA from further seizures; that injunction was overturned in 1979. In a separate decision, a judge set up a system under which a patient could get laetrile for personal use if a physician signed an affidavit that the individual was terminally ill, but his system was voided in 1987. As a result of these decisions, it is illegal to transport laetrile across state lines or into the United States, even with a physician's prescription.

Federal District Judge Luther Bohanon who established the affidavit system for laetrile in 1977 offered his considered view of the controversy:

Advocates of laetrile's use in cancer treatment include many highly educated and prominent doctors and scientists whose familiarity and practical experience with the substance vastly exceeds that of their detractors. To deem such advocacy "quackery" distorts the serious issues posed by laetrile's prominence and requires disregarding considerable expertise mustered on the drug's behalf.

While the record reveals an impressive consensus among the nation's large medical and cancer-fighting institutions as to laetrile's ineffectualness, a disconcerting dearth of experience with the substance by such detractors is revealed...

The current debate is fierce. The issue appears largely unresolved as to laetrile's true effectiveness, in large part because FDA has prevented adequate testing on humans....

It is only when the substance is openly used, and its results carefully observed and fully reported that this controversy will be resolved.{176}

{114}114. N.M. Ellison et al., "Special Report on Laetrile: The NCI Laetrile Review," New England Journal of Medicine 299(10):549-552 (1978). In Office of Technology Assessment, Unconventional Cancer Treatments,102.

{115}115. Michael L.Culbert, D.Sc., "Apricot Power: Laetrile as the Marine Corps of the `Alternative' Revolution," Townsend Letter for Doctors (June 1995), 71.

{116}116. Ralph W. Moss, The Cancer Industry: Unravelling the Politics (New York: Paragon House, 1989), 134-5.

{117}117. Ibid., 135.

{118}118. Ibid., 132.

{119}119. Anonymous, "The Committee for Freedom of Choice," CA - A Cancer Journal for Clinicians (May/June 1991). In Townsend Letter for Doctors (February/March 1992), 194.

{120}120. Anonymous, "The Committee for Freedom of Choice." In Townsend Letter for Doctors

(February/March 1992), 195.

{121}121. Culbert, "Apricot Power," 72.

{122}122. Moss, The Cancer Industry, 122.

{123}123. W.H. Lewis and M.P.F. Elvin-Lewis, Medical Botany: Plants Affecting Man's Health (New York: John Wiley and Sons, 1977). In Office of Technology Assessment, Unconventional Cancer Treatments, 102.

{124}124. S. Takeuchi et al., "Benzaldehyde as a Carcinostatic Principle in Figs," Agricultural Biology and Chemistry 42:1449 (1978). In Office of Technology Assessment, Unconventional Cancer Treatments, 78.

{125}125. M.F. McCarty, "Cytostatic and Reverse-Transforming Therapies of Cancer - A Brief Review and Future Prospects," Medical Hypotheses 8(6):589-612 (June 1982).

{126}126. Bruce Halstead, Amygdalin (Laetrile) Therapy, Los Altos, CA: Choice Publications. 1978. In Culbert, "Apricot Power," 72.

{127}127. Moss, The Cancer Industry, 133.

{128}128. Culbert, "Apricot Power," 78.

{129}129. Anonymous, "The Committee for Freedom of Choice." In Townsend Letter for Doctors, 194.

{130}130. Kittler, Glenn D., Laetrile Control for Cancer (New York: Paperback Library, 1963.) In Richard A. Passwater, Cancer and Its Nutritional Therapies (New Caanan, CT: Keats Publishing, Inc., 1983).

{131}131. Moss, The Cancer Industry, 148.

{132}132. Michael Culbert, Freedom from Cancer (Seal Beach, CA: '76 Press, 1976). Cited in Moss, The Cancer Industry, 147.

{133}133. John A. Morrone, "Chemotherapy of Inoperable Cancer," Experimental Medicine and Surgery 4(1962). In Moss, The Cancer Industry, 147.

{134}134. B. Rossi et al., Proceedings of the Ninth International Cancer Congress, 1966. In Walters, Options, 184.

{135}135. U.S. Department of Health, Education and Welfare, Public Health Service, National Institutes of Health, National Cancer Institute, Office of Cancer Communications, "Background Information on Laetrile. NCI Testing of Laetrile in Animals," typescript, September 1977. In Office of Technology Assessment, Unconventional Cancer Treatments, 103.

{136}135. M.P. Chitnis et al., "Studies on High-dose Chemotherapy of Amygdalin in Murine P388

Lymphocytic Leukemia and P815 Mast Cell Leukemia," Journal of Cancer Research in Clinical Oncology 109:208-9 (1985).

G.J. Hill et al., "Failure of Amygdalin to Arrest B16 Melanoma and BW5147 AKR Leukemia," Cancer Research 36:2102-7 (1976). C.C. Stock et al., "Antitumor Tests of Amygdalin in Transplantable Animal Tumor Systems," Journal ofSurgical Oncology 10:81-8 (1978).

W.R. Laster, Jr. and F.M. Schabel, Jr., "Experimental Studies of the Antitumor Activity of Amygdalin MF (NSC-15780) Alone and in Combination With Beta-glucosidase (NSC-128056)," Cancer Chemotherapy Report, Part I, 59:951-65 (1975).

I. Wodinsky and J.K. Swiniardki, "Antitumor Activity of Amygdalin MF (NSC-15780) as a Single Agent and With Beta-glucosidase (NSC-128056) on a Spectrum of Transplantable Rodent Tumors," Cancer Chemotherapy Report, Part I, 59:939-50 (1975). In Office of Technology Assessment, Unconventional Cancer Treatments, 103.

{137}137. A.A. Ovejera et al., "Inactivity of DL-amygdalin Against Human Breast and Colon Xenografts in Athymic (Nude) Mice," Cancer Treatment Reports 62(4):576-8 (1978).

{138}138. Moss, The Cancer Industry, 144.

{139}139. Mark McCarthy, "Burying Caesar: An Analysis of the Laetrile Problem," Triton Times, University of California, San Diego, November 29, 1975. In Moss, The Cancer Industry, 144.

{140}140. P.G. Reitnauer, "Prolonged Survival of Tumor-Bearing Mice Following Feeding Bitter Almonds," Archives Geschwulstforschung (Dresden) 42:135 (1973). In Moss, The Cancer Industry, 144.

{141}141. Dean Burk, A Brief on Food and Vitamins (Sausalito, CA: McNaughton Foundation, 1975). In Moss, The Cancer Industry, 145.

{142}142. Culbert, "Apricot Power," 77

{143}143. Ibid.

{144}144. Ibid., 78.

{145}145. C.C. Stock, D.S. Martin, K. Sugiura et al., "Antitumor Tests of Amygdalin in Spontaneous Animal Tumor Systems," Journal of Surgical Oncology 10:89-123 (1978). In Office of Technology Assessment, Unconventional Cancer Treatments, 104.

{146}146. C.C. Stock, D.S. Martin, K. Sugiura et al., "Antitumor Tests of Amygdalin in Spontaneous Animal Tumor Systems," Journal of Surgical Oncology 10:89-123 (1978). In Office of Technology Assessment, Unconventional Cancer Treatments, 106.

{147}147. Moss, The Cancer Industry, 183.

{148}148. Sugiura, personal communication with Ralph Moss, 1979. In Moss, The Cancer Industry, 184.

{149}149. Anonymous, "The Committee for Freedom of Choice." In Townsend Letter for Doctors, 195.

{150}150. Harold Manner et al., The Death of Cancer (Chicago: Advanced Century Publishing

Corporation, 1978). In Moss, The Cancer Industry, 145.

{151}151. Ibid., 145-6.

{152}152. H. Manner et al., "Amygdalin, Vitamin A and Enzyme Induced Regression of Murine

Mammary Adenocarcinomas, Journal of Manipulative Physiological Therapies 1(4):246-8 (1978).

{153}153. Office of Technology Assessment, Unconventional Cancer Treatments, 104.

{154}154. Moss, The Cancer Industry, 146.

{155}155. N.M. Ellison et al., "Special Report on Laetrile: The NCI Laetrile Review," New England Journal of Medicine 299(10):549-552 (1978).

{156}156. C.G. Moertel et al., "A Pharmacologic and Toxicological Study of Amygdalin," Journal of the American Medical Association 245(6):591-4 (1981).

{157}157. C.G. Moertel et al, "A Clinical Trial of Amygdalin (Laetrile) in the Treatment of Human

Cancer," New England Journal of Medicine 306(4):201-6 (1982). In Office of Technology Assessment, Unconventional Cancer Treatments, 106-7.

{158}158. Office of Technology Assessment, Unconventional Cancer Treatments, 107.

{159}159. M.L. Culbert, correspondence, New England Journal of Medicine 307(2):119 (1982).

{160}160. Office of Technology Assessment, Unconventional Cancer Treatments, 107.

{161}161. Culbert, "Apricot Power," 81.

{162}162. Ibid.

{163}163. Ibid.

{164}164. Walters, Options, 184.

{165}165. Anonymous, "The Committee for Freedom of Choice." In Townsend Letter for Doctors, 196.

{166}166. E.S. Schmidt et al., "Laetrile Toxicity Studies in Dogs," Journal of the American Medical

Association 239(10):943-7 (1978). In Office of Technology Assessment, Unconventional Cancer

Treatments, 103.

{167}167. C.G. Moertel et al., "A Clinical Trial of Amygdalin (Laetrile) in the Treatment of Human

Cancer." In Office of Technology Assessment, Unconventional Cancer Treatments, 103.

{168}168. Journal of the American Medical Association (14 April, 1978). In Moss, The Cancer

Industry, 142.

{169}169. Moss, The Cancer Industry, 143.

{170}170. Culbert, "Apricot Power," 79.

{171}171. Ibid., 79-80.

{172}172. Ibid., 80.

{173}173. Ibid., 79-80.

{174}174. Anonymous, "The Committee for Freedom of Choice." In Townsend Letter for Doctors, 196-7.

{175}175. Culbert, "Apricot Power," 78.

{176}176. Luther Bohanon, "Opinion in the Case of Glen L. Rutherford vs. U.S.A. In the U.S. District  court for the Western Region of Oklahoma." No. CIV-75-0218-B. December 5, 1977. In Moss, The Cancer Industry, 150.

{177}177. Richard Thomas, The Essiac Report: Canada's Remarkable Unknown Cancer Cure (Los Angeles: The Alternative Treatment Information Network, 1993), 12.

{178}178. Gary Glum, The Calling of An Angel (Los Angeles: Silent Walker Publishing, 1988).

{179}179. Richard Thomas, The Essiac Report: Canada's Remarkable Unknown Cancer Cure (Los Angeles: The Alternative Treatment Information Network, 1993).