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Risky business: beyond media headlines

The 5DRs have been very concerned about the recent reports about processed meat and whether we should or shouldn’t be giving them up. We asked our resident research expert Dr Haloom Rafehi to look at the data and help us understand what is all means. 



Tabloid media loves a good disease related story, and while these can often be educational, they are often sensationalised, confusing and contradictory. One aspect of medical research that is often poorly communicated is risk.

As an example, let’s look at the recent media focus on the link between processed meat and colorectal cancer. The International Agency for Research on Cancer (IARC) recently released a report stating that for every 50 grams of processed meat consumed daily, an individual’s risk of developing colorectal cancer increases by 18%. Furthermore, news articles also reported that processed meat is classed as a group 1 category along with known carcinogens (cancer causing agents) such as cigarettes and asbestos.

Sounds pretty bad, doesn’t it? So why aren’t we all developing colorectal cancer? Fortunately for all lovers of processed meat such as sausages and salami, the media reporting, while technically truly, is highly misleading.

First of all, overall (or absolute) risk of developing colorectal cancer is not 18% – rather, those who eat 50 grams of daily are 18% more likely to develop colorectal cancer compared to those who do not. While 18% sounds like a huge number, it is actually a 1.18 times increase – less than a doubling.

It is estimated that Australians who live to age of 85 years of age have an 8.2% chance of developing bowel cancer. That means for every 100 Australians, between 8-9 individuals will develop colorectal cancer by the age of 85. For the sake of simplicity, let’s assume that this statistic is based on a population that eats no processed meat at all – what would happen if everyone suddenly started eating 50 grams a day? The 8.2% risk would increase by 18%. That equals 1.47%. When we add that back to the original 8.2% risk, we now get a new absolute risk estimation of 9.6%. In other words, we have gone from 8-9 cases of colorectal cancer for every 100 Australians to 9-10 cases. That is a much smaller increase compared to the original 18%.

Furthermore, reports that the IARC classed processed meat in the same category as smoking and asbestos are also misleading. The group 1 category does not refer to the how strongly something causes cancer, as one might assume. Instead, it refers to the strength of the evidence and research used to identify the increased cancer risk. In other words, smoking is listed in group 1 because there is strong evidence that it confers a very strong risk of developing lung cancer. In contrast, processed meat is listed in group 1 because there is strong evidence that it can increase cancer risk, but only by a small amount. Some estimates indicate that smoking causes up to 21% of all cancer-related deaths. Eating processed meat does not even come to that figure.

Of course, this does not mean that we should eat as much sausage and salami as we like. It has been well known for a long time that processed meats are not very healthy – they are high in salt and, more often than not, very high in unhealthy saturated fats. They should only be consumed in a limited quantity. However, overstating the cancer risk also causes unnecessary worry and guilt. I hope that the next time you come across health reporting in the media, you will remember this topical example and approach with caution.

For those interested in learning more, I have collated some useful resources on the topic:

The original report by the International Agency for Research on Cancer (IARC):

https://www.iarc.fr/en/media-centre/pr/2015/pdfs/pr240_E.pdf

A great video explaining this issue by the team at SciShow:

https://www.youtube.com/watch?v=UqvXc4q0NyM

A comprehensive article further discussing this issue, published in the conversation:

http://theconversation.com/confused-about-your-cancer-risk-from-eating-meat-heres-what-the-figures-mean-49888

A relevant article about the sensationalist reporting about cooking oils causing cancer by an Australian cancer researcher:

http://theconversation.com/cooking-the-books-when-that-sensational-new-research-finding-isnt-all-it-seems-50386


Dr HR