網路上找到這一篇文章，把這件事講的滿清楚的。
連結在此
http://www.quackwatch.com/01QuackeryRelatedTopics/Cancer/laetrile.html
節錄其中一段關於NCI(National Cancer Institute)做的臨床研究
In July 1980, the NCI undertook clinical trials of 178
cancer patients who received Laetrile, vitamins and enzymes
at the Mayo Clinic and three other prominent cancer
centers. The study included patients for whom no other
treatment had been effective or for whom no proven
treatment was known. All patients had tumor masses that
could easily be measured, but most of the patients were in
good physical condition. Since Laetrile proponents were
unable to agree on the formula or testing protocol for
Laetrile, NCI decided to use a preparation that
corresponded to the substance distributed by the major
Mexican supplier, American Biologics. The preparation was
supplied by the NCI Pharmaceutical Resources Branch and
verified by a variety of tests. The dosage of Laetrile was
based on the published recommendations of Krebs, Jr., and
the Bradford Foundation.
The results of the trial were clear-cut. Not one patient
was cured or even stabilized. The median survival rate was
4.8 months from the start of therapy, and in those still
alive after seven months, tumor size had increased. This
was the expected result for patients receiving no treatment
at all. In addition, several patients experienced symptoms
of cyanide toxicity or had blood levels of cyanide
approaching the lethal range [8]. An accompanying editorial
concluded:
簡單的解釋一下這段，1980年8月， NCI找了178名自願的癌症病患
來做杏素治療的臨床試驗，這些病人包括了一些其他療法都無效的
病患，這些病患的腫瘤都已經發展至足以量測的大小，且身體條件
良好。給予病患服用的劑量則按照Krebs, Jr.的建議。
試驗的結果相當清楚，沒有任何一個病患是痊癒的，甚至沒有人出
現病情穩定的結果。這些病患的存活時間的中位數是4.8個月(從開
始接受療程算起)，少數人可以活到7個月後，不過腫瘤的大小也成
長了。這樣的結果和未受任何療程下的預期結果差不多。此外，有
數位病患出現氰中毒或是血中氰化物濃度過高的現像。