Sloan-Kettering's own study found laetrile slowed mouse tumors — the hospital buried it

In 1972 America's most famous cancer hospital decided to settle the laetrile question. Benno Schmidt, a Memorial Sloan-Kettering board member, convinced the center to test the apricot-pit extract so it could assert the drug's ineffectiveness 'with some conviction'. The work went to Kanematsu Sugiura, a pioneer who had built his career on 250 published papers and had retired from the center a decade earlier without actually leaving his bench.

The mice did not cooperate. In Sugiura's studies, laetrile 'significantly inhibits the appearance of lung metastasis in mice bearing spontaneous mammary tumors' and slowed the growth of the primary tumors themselves. A blind test could not confirm anticancer activity, but the positive findings were impossible to ignore — so the institute ignored them: Chester Stock, Sugiura's supervisor, declined to publish the results because they 'would have caused all kind of havoc'. They leaked anyway, in 1973, and caused the stir he had predicted.

Over the next four years the institute tested laetrile across 14 tumor systems, and in June 1977 it released its verdict: no beneficial effects. The report was scientifically defensible and institutionally disastrous. It contained errors that laetrile's backers seized on, and Nicholas Wade noted in Science that 'even the appearance of a departure from strict objectivity is unfortunate'. President Lewis Thomas insisted there was 'not a particle of scientific evidence' for the drug — while inside the center, staff were preparing to say the research had been mishandled.

In November 1977 a group of staff, including public affairs official Ralph Moss, released a 48-page report charging that the laetrile research was 'incomplete and scientifically invalid'. Moss was fired for co-authoring it. 'There has been a cover-up', he said — that sentence, not the mouse data, became laetrile's strongest argument. The science was vindicated: the studies were published in 1978, no other laboratory could reproduce them, and a 1982 Mayo Clinic trial of 175 patients found the drug useless. The suppressed report sits in the center's own archive, filed under its own name.