Question: is there anything in particular that causes our cells to grow out of control? why do some people get cancer and others don't?

Ian Hands-Portman answered on 11 Mar 2014:

Loads of things!

There are lots of different genes involved in controlling how and when cells divide, changes to any of them can cause a cell to become cancer. About 10% of cancer is down to inheriting a bad gene.

Simply getting old means our cells pick up mutations in their DNA as they divide and sooner or later if you live long enough one of your cells will get a cancer mutation; a third of us will get cancer at some point in our lives – because we’ve stopped dying of infections and being eaten by bears before we have a chance to get it.

Some things do increase your risk though –

Smoke contains a lot of chemicals that can stick to your DNA and either alter it or make your cells misread it when they divide.

UV light from the sun does it by breaking DNA and our cells have to make a guess when they patch up the damage, that can make them mutate.

Those are things we can control our exposure to – don’t smoke and don’t get sunburn but there are other causes –

Viruses – some viruses can cause cancer – Have you heard of the HPV vaccine? It’s important as HPV ( human papilloma virus ) which normally causes warts can also cause cancer in some people – it turns off a protein that controls cell division and probably causes around 5% of all cancers, other viruses just overwrite our DNA and cause havoc that way.

I don’t want to frighten you with any of this – the simple fact is we are mortal and have to die of something but the vast majority of us won’t have to worry about it until we’re old and loosing our marbles anyway.