What is cancer?

Around the world, more than 14 million people are diagnosed with cancer every year, and that figure is expected to rise to more than 21 million by the year 2030 so it’s a growing global problem. Kat Arney spoke to Emma Smith, science communications manager at Cancer Research UK, to get the basics about cancer.

Emma - Normally cells are very highly controlled. They grow only when your body needs them and when there are signals to do so. Now in cancer, some of these signals, some of the genes in the cells have gone haywire. For some reason the cells start dividing and multiplying out of control and then you have too many of a certain kind of cell, and that’s when you get a tumour forming.

Kat - Are we talking about cancer as one disease? There is the ‘big C’ - is it just one kind of thing?

Emma - Absolutely not! We are made up of hundreds of different types of cells and cancer can appear in lots of different tissues: the bowel, the lung, the pancreas, everything and all these different types of cancer have different characteristics. They’re caused by different faulty molecules and different faulty genes and, of course, that will require different treatments. So we absolutely cannot treat cancer as one type of disease.

Kat - What do we know about what causes different types of cancer? People blame things in the environment, people blame stress, some people say well, it’s just in your genes isn’t it?

Emma - It’s a really, really complicated mixture of all of it. Some of it is down to things that we do, ways we live our lives, things in our environment. We call these preventable causes of cancer. These are things in our environment that can cause damage to our DNA, and it’s this damage to our DNA that introduces a fault and the faulty gene can accidently tell the cell to start multiplying and, bingo, you’ve got a cancer.

But, of course, that’s not the end of the story. Some of cancer is down to - I’ve seen it called in headlines “bad luck.” Well, let's not call it bad luck, let's just call in nature instead. All of our cells are capable of dividing and, every time they divide, unfortunately, as much as we would like to believe it, humans aren’t perfect. As a cell copies itself and copies its DNA, it can just accidentally introduce a mistake. It’s not a 100% perfect process and just by doing so, again you can end up with a fault in a key gene and possibly cancer developing.  So that’s the kind of nature side of it.

But chemicals and things in our environment can also introduce these DNA mistakes, so it is a mixture of both. Around 4 in 10 cancers are, let's call them “preventable,” so there are lots and lots of things that people can do if they want to reduce their cancer risk.

Kat - You’ve mentioned faulty genes and molecules can drive cancer. So how much cancer is actually in the genes? Can it be inherited - what’s the story there?

Emma - It can be inherited. There are certain examples where people inherit a fault from either of their parents and this particular gene is a really important and, therefore, it increases a risk of cancer. But this is really a minority of cancers. Most cancers are simply a result of nature, or simply getting older. Because damage builds up in our cells over time; all those things that I mentioned in our environment. So there are certains genes, but these form a very small proportion of cancers that we see.

Kat - So, so far we know that cancer is not one disease; it’s many different diseases. There are complex causes. There’s an interplay between the things in our environment, the things we do, and the things in our body itself. But then how do we treat cancer? Presumably, it’s not one size fits all for treatment either?

Emma - Absolutely not, but treatments can be broadly grouped into categories. Drugs that often make the headlines and modern drugs are very expensive. But these drugs aim to specifically home in and target cancer cells; they’re called targeted therapies. Chemotherapy, which is one of the cornerstones of cancer treatment. It’s more general in that it’s not specifically designed just to hit cancer cells but it is, in some cases, very, very effective. The other is radiation treatment, so radiotherapy and, of course, surgery. Put them all together and, usually, patients receive a mixture as well. They don’t just receive one therapy; normally it’s a combination of several different types of therapy.