Question: how do you get cancer

Douglas Blane answered on 20 Jun 2010:

First thing to say is cancer isn’t a disease that usually affects young people. It does happen but it’s not something you should worry about.

That said if you’re a young woman it’s worth learning the normal structure of your breasts: http://www.cancerhelp.org.uk/type/breast-cancer/about/finding-breast-cancer-early.

If you’re a young man it’s worth learning how to examine your testicles: http://www.cancerhelp.org.uk/type/testicular-cancer/about/testicular-selfexamination

It’s a good idea to talk to a nurse or doctor about both of these, as well as reading about them. Both parts of the body feel a bit lumpy anyway, and you can easily start worrying about stuff that’s perfectly normal.

You should see a doctor if there’s a sore or discoloured part of your skin that doesn’t heal within a month. If you get a hard lump anywhere in your body you should see a doctor. But don’t get obsessed about cancer. It is uncommon in young people.

So what about the science? Well cancer is a lot of different illnesses. What they all have in common is that the body’s own cells start multiplying out of control. Once you have a lot of cancer cells in one part of your body – which is called a tumour – they can spread to other parts. It’s then difficult to get rid of them.

A normal cell turns into a cancer cell when something goes wrong with the instructions every cell has inside it. These instructions are called DNA.

Have a look here to learn a little more about this: http://learn.genetics.utah.edu/content/begin/tour/

What makes these things go wrong? Well DNA is a long string (actually a double helix) of smaller molecules linked together. Each of these can be changed or damaged. Radiation, viruses and chemicals can cause these changes.

The DNA in a cell has to be copied every time that cell divides – and mistakes can happen then too.

Whatever the cause, all these changes in the DNA are given the same name – mutations. Sometimes a mutation will make the cell work better, but only very occasionally. Any random change to a complex system usually makes it worse.

Mutations are happening in our cells all the time. Almost all get fixed, because our cells have repair machinery inside them – like a bunch of microscopic plumbers, plasterers and electricians.

Some mutations turn a normal cell into a cancer cell by affecting how it grows and divides. If the repair machinery doesn’t fix this right away, that’s the start of cancer.

In a cancer cell the instructions have gone wrong in such a way that it keeps dividing out of control. Each time a cell divides in two it passes the instructions to keep on dividing to both daughter cells. That’s how the cancer grows

What all this means is that anything that causes more mutations in a cell could cause the kind of mutation that turns a normal cell into a cancer cell. As I mentioned, radiation can do this. Some viruses do it. A number of chemicals do it.

Chemicals that can cause cancer-type mutations in cells are called carcinogens. Tobacco smoke contains 50 known carcinogens.

I’m sorry this answer is so long. Your question is a good one. But it’s much easier to ask than to answer. 🙂