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Saturday, October 31, 2015

Warning: News headlines cause cancer

Earlier this week, according to numerous news headlines, the World Health Organization declared bacon just as carcinogenic as cigarettes and asbestos. "Red alert for meat eaters: WHO study finds hot dogs, bacon and other processed meats cause cancer," declared the Pittsburgh Post Gazette. The Telegraph proclaimed "Processed meat ranks alongside smoking as major cause of cancer, World Health Organisation says." The New York Post ran the story under the headline "OMG! Bacon causes cancer"; in related news, whoever wrote that headline should be arrested. Partisan sites weighed in with their own spin, with Fox News reporting "Meat producers blast WHO report linking processed meat and cancer" and PETA titling their story "Bacon-Wrapped Cancer."
Problem is, none of those headlines are an accurate reflection of the WHO study.
Here's the problem with scientific journal articles - hardly anybody actually reads them. What we read is some journalist's attempt to make the story more palatable to the general public. Most people don't realize that by the time the scientific study reaches our eyeballs, it has usually been shunted through a long and complex game of telephone.
The Skeptics with a K podcast did a story back in June explaining how it is that science headlines manage to get things so terribly wrong. The team explained that after a journal publishes an article, a press release is issued discussing the salient points. The press release is likely written by someone who didn't actually participate in the study, so that's step one in the telephone game. The press release ends up on the desk of a reporter, who probably does not read the actual journal article, and may or may not understand the science discussed in the press release. That reporter churns out a story, and that's step 2 of the telephone game. So it turns out that reporters usually don't write their own headlines, that's generally done later by a headline writer. The headline writer skims the article, which they may or may not understand, and gives it a headline, step 3 of the telephone game. Once the story is released into the wild, websites pick it up, often replacing the headline with a more sensational headline, designed to attract as many clicks as possible, telephone game step 4. Then of course there are the pundits and editorialists and bloggers who twist the data to serve their own ends, and the actual message ends up looking nothing like the one we started with.
So a few days ago, the journal Lancet Oncology published Carcinogenicity of consumption of red and processed meat by a group of scientists acting on behalf of the International Agency for Research on Cancer Monograph Working Group. Yawning yet? It gets yawnier. Those scientists performed a metadata analysis on all recent studies regarding the link between red and processed meats and cancer. They found that the majority of reliable studies show that people who eat a lot of processed meat have a slightly (but statistically significantly) greater risk of contracting some types of cancer. So they concluded, "On the basis of the large amount of data and the consistent associations of colorectal cancer with consumption of processed meat across studies in different populations, which make chance, bias, and confounding unlikely as explanations, a majority of the Working Group concluded that there is sufficient evidence in human beings for the carcinogenicity of the consumption of processed meat."
The WHO did not say that bacon is as bad as smoking - that misconception comes from the fact that the WHO labeled processed meats a Group 1 carcinogen. Group 1 does include cigarettes and asbestos, but it also includes sawdust, the sun, and alcoholic beverages. To be in Group 1, research must show significant evidence that the agent causes cancer; Group 1 doesn't care about the degree of carcinogenicity or the amount of the agent that the subject must be exposed to. The article doesn't make any of the outlandish claims that the headlines alluded to - in fact, the group clarified that "the latest IARC review does not ask people to stop eating processed meats but indicates that reducing consumption of these products can reduce the risk of colorectal cancer."
It worries me that newspaper headlines can make us more, rather than less, ignorant.


jenny_o said...

Even the so-called experts don't appear to be reading the studies. The CBC national news (our most reliable news source in Canada, and mostly very good) did an interview with their usual doctor source, and she addressed neither the fact that the increase in risk is minute nor the reason processed meats were placed in the new category. Her advice was just to cut back on consumption. I'm not sure how information from medical studies is supposed to get to the public accurately.

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