1 in 2 cancer statistic.

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So when the “1 in 2 of us will get cancer” statistic comes up on TV, is it right that us and the person we’re sitting with are wondering who will get it?

That doesn’t seem to make sense to me, but at the same time I can’t explain it.

So does “1 in 2”, “1 in 10” etc mean “2 people sat on a couch, 1 of you is getting cancer”, “look at 10 people in the street and 1 will get cancer”?

EDIT: cheers everyone for your explanations! Colour me informed.

In: Biology
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It just means that the cancer rate in whichever country the stat is from is roughly 50%.

This, of course, doesn’t mean that in every possible group of 2 people there will be 1 who gets cancer. But in your example of a random group of 10 people on the street, you would expect roughly 5 of them to do so.

Statistics are measures of groups. So, yes, in a sense given a 1 in 2 chance, for any group of 2 persons one is likely to get the disease. But it is a statistic on a very large group – so there is no guarantee that in small samples.

One way to think about it is using coin flips. 1 in every 2 flips is expected to be heads. But if you flip the coin and it comes up tails, this does not guarantee that the next flip MUST be heads. There is no way to predict individual outcomes with certainty using a group statistic (unless the probability is 0 or 1 ie it will never happen or it will always happen)

Think about how roughly half of people are born female and roughly half are born male. So you could similarly say that in a room of two people, it’s likely that one will be male and one female. But it’s definitely not always true. It’s just a way to make the statistic easier the visualize.

Cancer is inevitable. Eventually, if you were to live long enough and avoid all other forms of death, you would get cancer, and if that didn’t kill you you’d keep on getting more cancer until you eventually did. Cancer happens when cells start to break, basically. More and more systems stop working properly as a result of accumulated mutations until they’re growing into tumours. So, when someone says 1 in 2 people will get cancer, what that really means is that 1 in 2 people will successfully avoid dying before they get cancer.

Also, no, 1 in 2 doesn’t literally mean that one of you and the person next to you will get cancer. It just means that of the population as a whole, 50% will get cancer. This is influenced by a lot of things, but will mean that some people will get cancer more than others. If you were to go into a room full of raging alcoholics, the cancer rate in there would probably be quite a lot higher than 50%, whereas if you go into a room full of health freaks (but the kind who actually know what they’re doing), the rate would be quite a lot lower than 50%.

People used to die more.

I am 29 years old. Without modern medicine, I would have died at age 19, when I got a bad infection that turned septic. I needed antibiotics and an operation to clean out the wound in order to save my life.

But I might not have lived to 19. When I was 12, I had appendicitis. That has a 30% mortality rate without operating – even if you give the person antibiotics. It would be higher still without modern hospitals and care.

But I might not have lived to see 12, either. I got acute bronchitis at age 2. I was in ICU. Without modern medicine, I absolutely would have died as a toddler.

Of course, none of that would have mattered. I was a premature baby. I wouldn’t have survived my own birth if I’d been born even a couple of generations ago.

I am not unusual. If you were to examine literally anyone’s life, you would see how modern medicine has protected them and extended their life. It begins with birth. Then vaccinations – whether or not they actually receive them. Then medical care through their life. Dental care. Good (or at least plentiful) food. These things prevent the kind of deaths that were common very recently.

My grandfather had TB, my great-grandfather had polio. These illnesses no longer concern us.

So when we don’t die from other things, what is left? We have to die from something. Cancer eventually turns up if you live long enough. So does heart failure. That is why 1 in 2 people get cancer: because now we can fix most other problems.