Laetrile has been used as an anticancer treatment in humans worldwide. Although many anecdotal reports and case reports are available, findings from only two clinical trials [2,3] have been published. No controlled clinical trial (a trial including a comparison group that receives no additional treatment, a placebo, or another treatment) of laetrile has ever been conducted.
Case reports and reports of case series have provided little evidence to support laetrile as an anticancer treatment.[1,4,5,6,7,8] The absence of a uniform documentation of cancer diagnosis, the use of conventional therapies in combination with laetrile, and variations in the dose and duration of laetrile therapy complicate evaluation of the data. In a case series published in 1962, findings from ten patients with various types of metastatic cancer were reported. These patients had been treated with a wide range of doses of intravenous Laetrile (total dose range, 9-133 g). Pain relief (reduction or elimination) was the primary benefit reported. Some objective responses (responses that are measured rather than based on opinion), such as decreased adenopathy (swollen lymph nodes) and decreased tumor size, were noted. Information on prior or concurrent therapy was provided; however, patients were not followed long-term to determine whether the benefits continued after treatment was stopped. Another case series that was published in 1953 included 44 cancer patients and found no evidence of objective response that could be attributed to laetrile. Most patients with reported cancer regression in this series received recent or concurrent radiation therapy or chemotherapy. Thus, it is impossible to determine which treatment produced the positive results.
Melanoma is a malignant tumor of melanocytes, which are the cells that make the pigment melanin and are derived from the neural crest. Although most melanomas arise in the skin, they may also arise from mucosal surfaces or at other sites to which neural crest cells migrate, including the uveal tract. Uveal melanomas differ significantly from cutaneous melanoma in incidence, prognostic factors, molecular characteristics, and treatment. (Refer to the PDQ summary on Intraocular (Uveal) Melanoma Treatment...
Benzaldehyde, which is one of laetrile's breakdown products, has also been tested for anticancer activity in humans. Two clinical series reported a number of responses to benzaldehyde in patients with advanced cancer for whom standard therapy had failed.[10,11] In one series, 19 complete responses and ten partial responses were reported among 57 patients who had received either oral or rectal beta-cyclodextrin benzaldehyde; however, precise response durations were specified for only two of the patients. Another series by the same investigators used 4,6-benzylidene-alpha-D-glucose, which is an intravenous formulation of benzaldehyde. In this series, seven complete responses and 29 partial responses were reported among 65 patients, with response durations ranging from 1.5 to 27 months. No toxicity was associated with either preparation of benzaldehyde, and it was reported that the responses persisted as long as treatment was continued. Almost all of the patients in these two series had been treated previously with chemotherapy or radiation therapy, but the elapsed time before the initiation of benzaldehyde treatment was not disclosed.