Why Don't We All Get Cancer?

How causes of cancer interact
If you have read through you may be forgiven for thinking that with that number of potential causes, everyone will get cancer. But not everyone does. So why do some people get it and others don't? As ever, there are a number of different factors working together and these are outlined on this page.

'Risky' behaviour
This just means indulging in something that increases your risk. It may be smoking, or drinking too much, or eating a very unhealthy diet. Some of us look after ourselves better than others. And this can have a real effect on our health. But some people look after themselves really well and still get cancer. While others don't seem to look after themselves at all and never do.

Genetic predisposition
You may hear doctors or scientists talk about genetic predisposition to cancer. This means that your genetic make up makes it more likely that you will develop cancer.

It is not common, but there are such things as cancer families. These families have a much higher incidence of cancer than other families in the population. This may be particular types of cancer. But some families have all sorts of different cancers turning up in their family tree. They probably have a change (mutation) in a gene that is crucial in the development of many different cancers. Researchers often ask such families to help them in their research. Their genetic make up provides clues that help to show which genes are the most important in causing cancer.

For most people who may have a general susceptibility to getting cancer, it is not very obvious. Many of us probably have particular genes that are not very important in cancer development, but may increase our risk a little. For example, the cells of the lining of the lungs may be more likely to be damaged by cigarette smoke for person 'A' compared to person 'B'. It is more likely that person 'A' will develop a cancer than person 'B' who does not have that affected gene, even if they both smoke.

Cancer specialists believe that the younger someone is when they develop an 'adult' cancer, the more likely it is that there are genetic factors at work.

Chance
Many changes in genes are accidental. Cells divide and each time they do, they have to copy their genetic code completely. Sometimes mistakes happen. Many of these accidents would be fatal and make the daughter cells die. Sometimes the damage is repaired. Some changes wouldn't make very much difference to how the cell works. But they may take that cell one step further along the road to becoming cancerous.

Very many people with cancer, and their families, find this aspect of their cancer very difficult to come to terms with. It can sometimes make cancer easier to deal with if you understand why you have it.

Your immune system
The balance between the immune system and cancer is complicated. There is more about this in the section on the immune system in the causes of cancer section

Age
Some doctors say that if all men lived long enough they would get prostate cancer. It is true that the longer we live, the more likely we are to gather enough genetic damage to start a cancer off. Most of us die of something else, such as old age or other illnesses, before we get to that point.