Bacon raises cancer risk, but only slightly

Colorectal cancer is common, 5% of men get it, usually when very old, jumps to 6% with two pieces of bacon every day for rest of life.

HEALTH

Eating bacon raises cancer risks - slightly

29/10/2015
Justin Fox, Bloomberg View

You have of course heard the sad news about bacon. As the World Health Organisation's (WHO's) International Agency for Research on Cancer put it on Monday in a news release:

"The experts concluded that each 50-gramme portion of processed meat eaten daily increases the risk of colorectal cancer [bowel cancer] by 18%."

TWO PIECES OF BACON, EVERYDAY, FOR THE REST OF YOUR LIFE

How much is 50 grammes of processed meat? In bacon terms it's about two slices. Just to be clear, it isn't that eating two pieces of bacon will increase your colorectal cancer risk by 18%.

It's that eating two pieces of bacon every day for the rest of your life will.

But here's the important question that isn't directly addressed in the pages and pages of information released on Monday:

What's the risk of colorectal cancer to begin with?

RELATIVE RISK CAN BE DECEIVING

To illustrate how much this can matter: In 1995, the UK... issued a warning that third generation oral contraceptive pills increased the risk of thrombosis by 100%.

What that meant was that the risk of getting thrombosis -- potentially life-threatening blood clots in the legs or lungs -- went from one in 7,000 for women taking second generation birth control pills to two in 7,000 for those taking the third generation variety.

Not a huge risk, then.

But a 100% risk increase sounds quite ominous.

The warning scared many women away from the pill (as psychologist Gerd Gigerenzer describes in his book Risk Savvy).

One result was an estimated 13,000 additional abortions the following year in England and Wales.

Another was, ironically, a lot of thrombosis cases -- pregnancies and abortions are much more likely to bring on the condition than does taking a third generation birth control pill.

5% CHANCE OF COLORECTAL CANCER, 2% CHANCE OF DIEING FROM IT

Information about relative risk (or percentage increase in risk, such as the 18% above) can be misleading, then, unless it's presented in the context of absolute risk.

So what's the absolute risk of getting colorectal cancer?

According to the National Cancer Institute, men 60 and younger face almost a 5% chance of getting colorectal cancer in their lifetimes, and a greater than 2% chance of dying from it. For women it's about 4.5% and 1.9%.

COLORECTAL CANCER COMMON, BUT LATE IN LIFE

Colorectal cancer, then, is a relatively common and deadly disease. It tends to hit people later in life, when they're eventually going to die of something in any case. But still, it's worth trying to avoid.

Let's say you're a man, you have about a 5% chance of eventually getting colorectal cancer, and you up your bacon consumption by two pieces a day.

That increases your cancer risk to almost 6% -- not a trivial jump.

BASED ON NINE DIFFERENT STUDIES OF COLORECTAL CANCER

Unlike the ill-advised and since-revoked US dietary recommendations against cholesterol, these processed-meat cancer-risk estimates are based on years and years of empirical research.

The 18% estimate comes from a 2011 meta-analysis, published in the open-source journal PLOS One, of nine different studies of colorectal cancer.

It wouldn't be unreasonable to make changes in your diet based on this evidence (and similar but weaker evidence on the link between red meat and cancer).

THE RIGHT WAY TO PRESENT RISKS

I like bacon a lot, but I'd rather have a five in 100 chance of getting colorectal cancer than a six in 100 chance.

Good on the World Health Organisation for getting the word out. What I don't understand, though, is why they didn't present the risks in those terms. 

BOWEL CANCER SPOTTED TOO LATE

Perhaps an even bigger problem is that, at least in the UK, thousands of people die each year because their colorectal or bowel cancer is spotted too late (for more info read BBC article here).

©2015 Bloomberg View

Justin Fox is a columnist writing about business. Prior to joining Bloomberg View, he was the editorial director of the Harvard Business Review.

http://www.bangkokpost.com/opinion/opinion/747280/eating-bacon-raises-cancer-risks-slightly

http://scienceblog.cancerresearchuk.org/2015/10/26/processed-meat-and-cancer-what-you-need-to-know/

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