DNA damage and its consequences
On top of this, the life-sustaining chemical reactions that occur naturally in our cells generate harmful by-products, and these can cause DNA damage. So merely ‘being alive’ can cause DNA damage and, potentially, cancer.
To make matters worse, our everyday surroundings are full of things, such as background radiation, sunlight and tobacco smoke, which constantly damage the DNA in our cells. As a result of this continuous bombardment, some studies have estimated that the DNA in a single human cell gets damaged over 10,000 times every day.
So why don't we constantly develop cancer?
Thankfully, cells have evolved many complex mechanisms to detect and repair DNA damage, and most of the time a cell repairs its damaged DNA without a problem. But, just like the machinery that copies DNA, a cell's repair machinery is not 100% efficient and not every single error is corrected.
So, as a back up, to prevent cancer occurring, there are systems that cause a damaged cell to commit suicide if the DNA damage is too severe. DNA repair and apoptosis (cell suicide) have been the subject of huge amounts of research. Cancer Research UK is heavily involved in funding this area of investigation.
Occasionally, despite all of these safety nets, the cell’s repair machinery fails to correct the DNA damage, but doesn't trigger the cell's suicide apparatus. And this is when cancer can occur. In fact, some of the most harmful cancer-causing mutations are mutations in the genes that regulate DNA repair and apoptosis. It is now thought that developing cancer is as much to do with the failure to repair DNA damage as it is to do with acquiring the mutations in the first place.
There are two other important types of genes that, when mutated, can cause cancer - tumour suppressor genes and oncogenes.
There are many other types of gene that can become mutated to make a cancer cell more 'successful' at surviving in the body. For example, some genes make proteins that allow the cell to travel down blood vessels, allowing a cancer cell to spread to other parts of the body. Others prevent damaged cells from being attacked by the body's immune system.
We are learning more and more all the time about how cancer cells live and grow in the body - with every new piece of the cellular jigsaw, we uncover another potential way to prevent, diagnose or treat cancer.
