There are hundreds of different types of cancer and most of us know at least one person that's been affected by it.
A cancer cell is one that refuses to die, dividing over and over again
What is it?
One in two of us will get cancer during our lives. And one in four of us will die from it. So everyone will know someone affected by this disease.
There are hundreds of different types of cancer - at least one for every bit of our body. Some are deadly but many are curable, and more people with cancer survive now than ever before.
Our bodies are made up of billions of tiny cells. Each cell grows, divides then dies in strict order. A cancer cell is one that refuses to die, dividing over and over again. It doesn't stop. Soon there are millions of cancer cells, all stubbornly refusing to die.
Why is this harmful?
The cancer can grow so big it can stop other bits of our body working properly. It can hurt. And it can wear us out.
Why do people get cancer?
For most cancers, there are two reasons.
- We inherit the risk in our genes. This doesn't mean you'll definitely get cancer if your Granny did. But for some types it may be slightly more likely.
- Something in our environment triggers it off and makes that first cancer cell refuse to die. Common triggers are cigarettes, sunlight and certain viruses.
How can I stop it happening?
- Because it's genetic we can't always avoid it by being on the alert. But we can hugely reduce our chances by doing the following:
- Don't smoke. Tobacco is responsible for more cancer deaths than anything else. And it's not just lung cancer either. Smoking causes cancer of the mouth, cervix, kidney, pancreas, bladder and stomach, too. Stub It Out.
- Slap on the Factor 50. Burning in the sun is not a good look and it whacks up our risk of dangerous skin cancers.
- Eat well. Doctors estimate that one in ten cancer cases are caused by unhealthy diets. Get your five fresh fruit and veg a day, and eat plenty of unprocessed, high fibre healthy foods.
- Exercise. Not just for the muscle definition. A 2011 study showed that 3 - 4% of all bowel, breast and womb cancers in the UK are linked to physical inactivity.
- Prevention. Cervical cancer is one of the most preventable and curable cancers. Early detection via a smear test could save your life and the HPV vaccine for 12 - 13 year old girls helps prevent you getting cervical cancer when you're older.
But cancer is for old people, right?
Cancer when we're young is extremely rare. But it does happen with skin cancer, testicular cancer and types of blood cancer. That doesn't mean we shouldn't look after ourselves now though - do you fancy looking back to wish you'd done things differently?
BBC Advice factfiles are here to help young people with a broad range of issues. They're based on advice from medical professionals, government bodies, charities and other relevant groups. Follow the links for more advice from these organisations.