The science behind the campaign
What is a mutation?
A mutation is a fault in our DNA. DNA carries the instructions for our cells, packaged in the form of genes – these instructions tell the cell how to behave. So faults in our DNA can alter the way a cell behaves. In the case of cancer, damage to our genes causes a cell or group of cells to start to divide and reproduce uncontrollably, often forming a lump or tumour.
What causes mutations?
Mutations can happen by chance when new cells are made as part of normal development or they can be caused by things such as the chemicals in cigarettes that damage the DNA. It is not easy for a normal cell to turn into a cancer cell as around half a dozen different mutations are needed before this happens. The body has ways of repairing mutations, and cells can also destroy themselves if the damage is severe. But these checks and balances aren't perfect, and sometimes mutations don't get repaired and cells don't destroy themselves. Many mutations will happen in parts of our DNA that aren't crucial to the functioning of the cell, but some will happen in important genes that the body relies on to stay healthy.
It can take a long time before enough mutations happen for a cell to become cancerous. This is why most types of cancer are more common in older people. Although mutations happen naturally in the body, smoking increases the number of mutations – this in turn increases the likelihood of developing enough mutations in crucial genes to cause cancer. Being a non-smoker helps stack the odds of developing cancer in your favour by reducing the number of mutations in your body.
Does every mutation lead to cancer?
No, most mutations will happen in parts of our DNA that aren't crucial to the cell's normal functioning. And many will either be repaired or the cell containing the mutation will die. But being exposed to the numerous cancer-causing chemicals in tobacco smoke increases the number of mutations, and therefore increases the chances of mutations happening in crucial genes that could lead to cancer.
If I stop, does the damage go away?
Smoking causes at least 14 different types of cancer, so if you are a smoker the best thing you can do for your health is to stop. Stopping smoking doesn't erase any mutations that have already happened but it reduces the number of mutations that are likely to happen in future. And once you quit the risk of cancer starts to decrease.
Are only older people and heavy smokers at risk?
No. Older people and heavy smokers are more likely to develop cancer but anyone can develop the disease. Cancer is more common in older people because there has been more time for mutations to accumulate over their lifetime. Heavy smokers will have been exposed to higher levels of chemicals and so be at increased risk, but even light smokers are more likely to develop cancer than non-smokers, and the length of time you smoke also plays a role – the longer you've smoked, the higher the risk of cancer.
Are only people who smoke cigarettes at risk, or those who smoke roll-ups too?
You are at risk whether you smoke cigarettes or roll-ups. Roll-ups expose smokers to over 4,000 toxic chemicals – many of which are carcinogenic and poisonous. Smoking roll-ups can result in the same health risks as smoking cigarettes, including cancer. In fact, studies have suggested that people who smoke roll-ups have an increased risk of cancer of the mouth, oesophagus, pharynx and larynx compared to smokers of manufactured cigarettes.
What evidence is there to support the campaign?
The campaign has been developed based on research from a number of well-respected sources including experts from the Wellcome Trust Sanger Institute, the Cancer Genome Atlas Network, the Institute of Cancer Research and the Broad Institute of Harvard and MIT.