Saturday, November 14, 2015
Getting to the meat of the issue.
I must say I don't blame the public for being annoyed at the announcement that eating red meat or bacon can increase your risk of getting cancer. Some articles even say you can put these foods in the same category as tobacco. And some medical sites on Facebook are having a field day scaring the public with the new information.
These data come from epidemiological studies that are notoriously difficult to carry out because they rely on people's memory of what they ate or drank years ago. And while some studies do show an association between these foods and cancer it is with one cancer, colon cancer, not all cancers. And to lump bacon and red meat in with tobacco is misleading and in fact ludicrous and perhaps harmful. If you make a bar graph of different lifestyle factors plotted against the risk of getting cancer the smoking bar would not only be the highest bar it would go through the the roof while the rest would stay on your table !
If you smoke and eat a lot of red meat and bacon quit smoking and your risk of getting a whole bunch of cancer will decrease dramatically. If instead you stop eating red meat and bacon but keep smoking you will see very little decrease in your risk of dying of cancer.
This is called the relative risk. While from a public health perspective it is useful to encourage people to eat a healthy diet the advice needs to be put in perspective. People enjoy eating. And if you expect them to respond to advice you need to temper the advice to take enjoyment and relative risk into account.
Here's another example of why you need to temper your advice. In the early 1980s I was at an international cancer congress in Seattle Washington when an article was published in the New England Journal of Medicine, a prestigious medical journal, by Brian McMann and equally prestigious epidemiologist, showing that drinking a lot of coffee increased the risk of getting pancreas cancer. The press ran with it and a real panic set in. I was director of the National Cancer Institute then and the Reagan White House called me and asked me what my position was. I said I thought the conclusion was flawed. They asked if I would hold a press conference and say so. It so happens I was asked to go on a morning TV show and talk about it. I walked out on the set with a mug of coffee in my hand. That made the point. No subsequent study ever confirmed the association of coffee with pancreas cancer. I used to joke with my staff that any study reporting an association of a lifestyle factor and cancer should be kept in a vault until a second study on the same subject became available to confirm or deny it. That won't happen of course but instead those of us in the medical profession who need to interpret these kinds of results for the public should proceed with more caution.