Laetrile: An Unproven Cancer Treatment
Laetrile is a chemically modified form of the chemical amygdalin. This compound occurs naturally in many fruit pits and nuts. French chemists first identified it in 1830. They found that when amygdalin breaks down, it produces the poison cyanide.Vitamin B17 is another name for laetrile, but it is not a vitamin. Some advocates believe cancer results from a vitamin deficiency that laetrile can presumably correct. Opponents think the term was coined to avoid federal drug safety and efficacy requirements.
Theories on LaetrileDuring the 1800s, doctors tried using amygdalin to treat cancer. It proved too toxic. In the 1950s, a semi-synthetic form, called laetrile, was produced and promoted as a cancer cure. Several theories exist about its anticancer action. In addition to the vitamin theory, some supporters believe an enzyme found primarily in cancer cells, but lacking in healthy cells, breaks down amygdalin. The amygdalin is broken down to cyanide, which then kills the cancer.Although some promote it as a cure, there is no scientific evidence of its success.
StudiesLaetrile gained notoriety during the 1970s, a time when doctors had fewer effective cancer treatments in their arsenal. Chemotherapy side effects were hard to control. Patients began looking for other options. Approximately 75,000 Americans had tried laetrile by 1978. That year, the National Cancer Institute (NCI) reviewed 93 cases submitted by doctors touting laetrile's benefits. Out of those 93 cases, only 6 actually showed benefits of tumor shrinkage.The NCI then sponsored research to evaluate laetrile. Two of the six patients in the first study died of cyanide poisoning after eating almonds. During the second study, patients received an infusion of amygdalin, followed by laetrile pills. Some patients reported feeling better while taking the drug. But cancer progressed in all 175 patients by the end of treatment. The NCI concluded that laetrile did not have any effect on treating cancer.Two recent reviews of laetrile did not turn up any randomized studies on the drug. Both reviews concluded that laetrile as cancer treatment has no clinical merit.