It's hard to uproot deeply held beliefs about cancer screening with scientific data.

很难用科学数据来根除人们对癌症筛查根深蒂固的观念。

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Scientists say the compound is likely to cause cancer but have no hard scientific proof.

科学家们称这种化合物可能致癌，但是并没有确凿的科学依据。

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People don't know there is an epidemic of cancer of the oesophagus, for example, which is very hard to treat.

比如，人们还不知道现在正流行食管癌，而这一病症是非常难以治疗的。

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During the course of treatment, however, they often develop resistance to a whole class of drugs at once a phenomenon known as multidrug resistance, which makes the cancer hard to treat.

ECONOMIST: Cell biology: The secret of the vaults | The

The incident was alarming because the fakes were billed as lifesaving drugs often prescribed to patients with hard-to-fight cancer.

WSJ: How Fake Avastin Penetrated U.S. Doctors' Offices

An experimental Pfizer (nyse: PFE - news - people ) pill shrank thyroid tumors, another hard-to-treat cancer.

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