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.

The supervisor vetoed publication to avoid havoc, but the leak and firing of Ralph Moss turned the cover-up into laetrile's strongest argument, costing credibility.

The board ordered science to close an argument: Schmidt had laetrile tested to assert its ineffectiveness 'with some conviction' — a study meant to win, no room for a result that refused to cooperate.

One supervisor's veto stood in for process: Chester Stock declined to publish Sugiura's positive findings because they 'would have caused all kind of havoc', and nobody could challenge him.

The public line froze before the data did: the June 1977 report declared no beneficial effects across 14 tumor systems, yet its errors let critics charge bias, and Science noted the appearance of it.

Firing the whistleblower turned a dispute into a censorship story: Ralph Moss, fired for saying 'there has been a cover-up', gave the laetrile movement exactly the martyr its campaign needed.

A buried result costs more than a published one: Sloan-Kettering was right about laetrile and still lost the argument, because the cover-up became the movement's best evidence.

In 1978 the laetrile studies were finally published together, and three other laboratories failed to confirm them. The 1982 Mayo Clinic trial of 175 patients called amygdalin 'a toxic drug that is not effective as a cancer treatment', and a 2015 Cochrane review closed the file: no sound evidence of benefit, real risk of cyanide poisoning. The affair left behind doubt about the institution, not the drug — the June 1977 report and Moss's firing gave the laetrile movement a grievance it organized around for years, and the 48-page casestudies.chat report survives in Sloan-Kettering's own archive.