Since the WHO’s International Agency for Research on Cancer announced on Monday that processed meats fall into the same cancer-risk category as tobacco smoke, we’ve been treated to thunderous headlines such as this one from the Guardian, “ Processed meats rank alongside smoking as cancer causes”. Most of these stories included a statement about how much additional risk bacon lovers were taking on:
The IARC’s experts concluded that each 50-gram (1.8-ounce) portion of processed meat eaten daily increased the risk of colorectal cancer by 18%
Sounds serious. But it’s entirely misleading. I know writers don’t write there own headlines but you would think editors would read at least a summary of the research before they impose this nonsense on the public.
Here is a quote from the World Health Organization’s Q and A accompanying their report:
Q. Processed meat was classified as carcinogenic to humans (Group 1). Tobacco
smoking and asbestos are also both classified as carcinogenic to humans (Group 1).
Does it mean that consumption of processed meat is as carcinogenic as tobacco
smoking and asbestos?
A. No, processed meat has been classified in the same category as causes of cancer such as
tobacco smoking and asbestos (IARC Group 1, carcinogenic to humans), but this does NOT
mean that they are all equally dangerous. The IARC classifications describe the strength of the
scientific evidence about an agent being a cause of cancer, rather than assessing the level of
risk. [emphasis added]
In other words, WHO has decided that there is now sufficient evidence that processed meat causes cancer and thus belongs in the category of known carcinogens such as cigarette smoke. But this says nothing about how large the influence is on cancer rates or how much additional risk bacon lovers incur.
In fact most of the stories I’ve read fail to explain that 18% increase in the risk of colorectal cancer. I’m no statistician but from what I understand it means this.
Colon cancer affects about 4.5% of the population. But an increase of 18% does not mean your cancer risk goes from 4.5 to 22.5%. It means that if you ate processed meat everyday your lifetime risk of getting colorectal cancer goes from 4.5% to 5.3%, an 18% increase from the baseline, not an absolute increase of 18%. Of course, from the perspective of world health, that is a lot of additional cancer. Health authorities are right to recommend guidelines that reduce consumption. But each individual’s increased risk is rather small. It’s a good idea to cut back if you’re a daily bacon hound, but occasional users—meh.
A lot more people will die from the stress of fear-inducing headlines than from eating a little smoked meat.