Question: How do people get cancer?

Natalia Brodaczewska answered on 7 Mar 2020:

As we go through life, the cells in our body keep dividing to make new cells and replace the old or damaged cells. But every time the cell divides, it has to make a copy of it’s whole DNA. Our DNA is very long (about 3 metres or 10 feet) and mistakes can happen during that process. Some of them get fixed by he cell. Some of them don’t make much difference to the cell and it keeps doing everything as it was. But some can cause changes to how the cell functions. For example, they can make some proteins more active, causing the cell to grow and divide faster than it should. Or sometimes, the change will mess up the proteins that repair the mistakes so that our cells become more likely to get more mistakes every time they divide. And this is usually how cancer forms – by collecting more and more of these ‘mistakes’ (scientists call them mutations or variants) so that eventually our cells start to grow and divide very fast and there is no way to control them. Finally, the cells may even learn to do things that they couldn’t do before, like being able to travel to other parts of the body and grow there – we call this process metastasis.

Sometimes, changes to our DNA can also be caused by the things that we are exposed to in our environment or even things that we eat or drink. Smoking and air pollutants can cause changes to the cells in our lungs, leading to lung cancer. UV rays from the sun can damage DNA in our skin if we get sunburnt many times, causing skin cancer. Alcohol and processed food can make changes to other cells in our body. This is why it’s important to live healthy lifestyles and protect our skin by using sunscreen in summer.