Understanding the risk of cancer requires an understanding of mathematics

Confusion of ingredient labels in grocery store.

Confusion of ingredient labels in grocery store. Source 

Maths was not my strong point when I was at school and when I became a pharmacist I spent a lot of time double checking my calculations. There is one hell of a big difference between a gram and a micro gram  

I also had a great deal of empathy for front of shop staff and their bewilderment with the concept of percentages. Understanding the basics of markup and markdown and margins are pretty fundamental to the profitability of any retail business. It is a skill that can be taught so it was important  to identify a potential problem from the start and it became standard practice of the staff interview process to ask the question

‘If an item retailing at $3.50 has had 50% added to its cost price. What did the item cost ? ”

It was extremely rare to get an answer of $2.33 and sometimes no matter how hard a person tried they just couldn’t get the concept that if you add 50% to a number X to get number Y and in turn take 50% off number Y it does not give you the number (X ) you started with .

This is a great article in The Conversation today Interactive body map: what really gives you cancer? 

But when scientists alternate between talking about cancer risk in percentages and whole numbers I can see why the world is very confused.  Let alone the concepts of relative and absolute risk

Relative risk

Relative risk compares the risk of cancer in one group of people to that in another group.

The chance of a group with a common risk factor (such as obesity) developing cancer can be compared to the chance of another group of people with a healthy weight. This relative risk ratio will remain constant across the world. But absolute risk will vary depending on how common a cancer is in a particular region.

Relative risk may sometimes be quite high and lead people to believe the absolute risk of developing disease is higher than it actually is.

For instance, a woman from a Western country has a 2 in 100 chance (2% absolute lifetime risk) of developing cancer of the endometrium (lining of the uterus) by the age of 85.

If the woman is obese, her risk of endometrial cancer is twice that of a woman of ideal weight. That is, a relative risk of 2 or 100% greater chance of developing endometrial cancer than a woman who is not obese.

This 100% figure may sound like obese women have a very high risk of endometrial cancer. But, in fact, the risk is still quite low, since doubling the 2% population risk still only makes the absolute risk of endometrial cancer in obese women around 4%. This is still a low probability of cancer.

Be careful not to confuse relative risk with absolute risk and remember the time-frames over which absolute risk can apply. Source 

I know I get exhausted doing the maths in my head whilst reading these articles and maybe its one of those things where a little bit of information is dangerous and causing unnecessary concern and its time to focus on helping people understand the basics of a healthy diet.



and dont forget your 30gms of fibre per day

'It says, 'If you want more fiber, eat the package.'

‘It says, ‘If you want more fiber, eat the package.’ Source