We reporters—or this one, at any rate—often fail to anticipate which stories will grip readers and which will quickly fade into oblivion. Given that, perhaps I shouldn’t have been surprised that a story I saw off to the printing press in the lull between Christmas and New Year’s engendered more comments than any other I’ve written.
The piece, which appeared online with the headline “The simple math that explains why you may (or may not) get cancer” (and in the magazine’s News section with the headline “The bad luck of cancer”), described a paper published in the 2 January issue of Science. As I and many other journalists explained, the study suggested that simple “bad luck”—random mutations accumulating in healthy stem cells—could explain about two-thirds of cancers, exceeding the risk conferred by environmental and genetic factors combined. One message was that some cancers could not be prevented and that detecting them early was key to combating them.
Readers wasted little time in skewering the authors, mathematician Cristian Tomasetti and cancer geneticist Bert Vogelstein of Johns Hopkins University in Baltimore, Maryland. Their statistics were faulty, some argued; they included many rare cancers and left out several common ones. Earlier today, the International Agency for Research on Cancer, the cancer arm of the World Health Organization, put out an unusual press release stating it “strongly disagrees” with the report. The agency said that “nearly half of all cancer cases worldwide can be prevented.” It charged that the authors’ push for early detection “if misinterpreted … could have serious negative consequences from both cancer research and public health perspectives.”
Reporters, if anything, fared worse. “Please, journalists, get a clue before you write about science,” pleaded an irate column in The Guardian, co-authored by an evolutionary biologist who goes by the Twitter handle @GrrlScientist and statistician Bob O’Hara at the Biodiversity and Climate Research Centre in Frankfurt, Germany.
Given the furor, I wondered: Had I gotten it wrong? Had the authors? Answering these apparently straightforward questions proved surprisingly difficult, exposing the challenges that come with communicating science, and the desire by scientist-authors and reporters to streamline the story they’re trying to tell.
I began with my own story, working backward to the science that spawned it. I’d written that the theory of random mutations in stem cells “explained two-thirds of all cancers.” Immediately, I knew that I had written part of that sloppily, to put it generously: The study didn’t include all cancers. In fact, it didn’t include two of the most common, prostate and breast, because the authors weren’t able to pin down the size of the stem cell compartment or the frequency of stem cell divisions in those tissues. Although my piece subsequently noted the number of cancer types in the study, I should have stressed the omissions early on.
Still, was “two-thirds” referring to the number of cases of cancers the study did include, as I and other journalists had suggested—or to something else? Journalists like numbers that abridge a study down to a bullet point. I’d wondered immediately if this two-thirds finding might be one such nugget. Tomasetti had explained to me in a lengthy interview that “if you go to the American Cancer Society website and you check what are the causes of cancer, you will find a list of either inherited or environmental things. We are saying two-thirds is neither of them.” I’d run the text of my “two-thirds” sentence by him prior to publication and he had had no objections (he had other clarifications).
Last week, we spoke again. Tomasetti had received more than 200 e-mails. Parents of children who had died of cancer were grateful that it might have occurred entirely by chance, suggesting that there was nothing they could have done. Biologists and statisticians were disputing his conclusions or simply surprised that so much of cancer might be random.
“We did not claim that two-thirds of cancer cases are due to bad luck,” Tomasetti told me gently. What the study argued, he explained, was that two-thirds of the variation in cancer rates in different tissues could be explained by random bad luck (a point made by others). What exactly did that mean, I wondered? Tomasetti, chatting by phone, had me draw some graphs to help me understand. By the end of the hour, I still wasn’t sure I grasped the essence.
Tomasetti was sympathetic. “There are lots of scientists that need clarification” on this paper, he said, along with some statisticians. He was busy preparing a technical report with additional details, and Johns Hopkins had just put out a press release explainer. “I honestly feel—and that’s what I told the BBC, and you can definitely quote me on this—overall, the reporters who interacted with us made a very honest and sincere effort to be as accurate as possible.”
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posted by f. sheikh