Lung cancer risks and causes
http://www.cancerhelp.org.uk/
This page tells you about risks and causes of lung cancer. You can find information on
* How common lung cancer is
* Smoking and lung cancer
* Other risk factors for lung cancer
* Diet and lung cancer
How common lung cancer is:
Lung cancer is the 2nd most common cancer in the United Kingdom (excluding non melanoma skin cancer). There are around 38,300 people diagnosed in the UK each year.
Smoking and lung cancer
In most people, lung cancer is related to cigarette smoking. Although some people who have never smoked get lung cancer, smoking causes 9 out of 10 cases.
Here are some facts about smoking and lung cancer
* The more you smoke, the more likely you are to get lung cancer but it is the length of time you have been a smoker that is most important
* Filtered and low tar cigarettes might not increase your risk quite so much, but most smokers cancel this out by taking more, deeper puffs or smoking more cigarettes
* As soon as you stop smoking, your risk of lung cancer starts to go down
* 15 years after you have stopped smoking, your lung cancer risk is almost the same as a non smoker
* Passive smoking (breathing other people's cigarette smoke) does increase the risk of lung cancer, but it is still much less than if you smoke yourself
How long you've smoked is very important. If you have smoked 20 a day for 40 years, your risk of lung cancer is about 8 times more than if you smoke 40 a day for 20 years.
It is almost impossible to work out the risk of occasional smoke exposure to secondhand smoke for non smokers (passive smoking). We know that the risk to passive smokers goes up the more cigarette smoke they are exposed to. Breathing in secondhand smoke at work can double lung cancer risk. Heavy exposure to secondhand smoke in childhood can increase the risk of lung cancer in adulthood by even more. Secondhand smoke at home in adults increases risk by about a third.
Cigarette smoking is the main cause of lung cancer. But pipe and cigar smokers are still much more likely to get lung cancer than non smokers. (They are also much more likely to get cancer of the mouth or lip.)
In the past lung cancer has always been more common in men than women. Now, as more women smoke, it is almost as common in women.
Other risk factors for lung cancer
There are some other things that increase lung cancer risk, but they increase the risk far less than smoking
* Exposure to radon gas
* Exposure to certain chemicals
* Air pollution
* Scarring from previous lung disease, for example tuberculosis (TB)
* A family history of lung cancer
* Past cancer treatment
Exposure to radon gas
Radon gas is a naturally occurring radioactive gas that can seep out of the soil into buildings. This is more likely in certain parts of the country where there is a lot of granite (for example, the West Country and the Peak District). Radon is the second biggest cause of lung cancer after smoking. It may cause almost 1 in 10 lung cancer cases. The risk from radon increases the risk from smoking. Smokers with high indoor levels of radon have a particularly high risk of getting lung cancer. If you are worried about this, the Health Protection Agency - Radiation Protection Division have information on how to check your house.
Exposure to certain chemicals
A number of substances may cause lung cancer, including asbestos, metal dust and fumes, paints, polycyclic aromatic hydrocarbons, diesel exhaust, herbicides, some types of insecticides and silica. These are rare causes of lung cancer because you would normally only come across these chemicals in large amounts if you worked with them. And not many people do.
Air pollution
Air pollution may cause lung cancer. We know this from studies on people exposed to large amounts of diesel exhaust fumes at work, for many years. This type of long term occupational exposure may increase lung cancer risk by up to 47% (that is the average risk of lung cancer, plus half again). One study has shown that people living in areas with high levels of nitrogen oxides (mainly from cars and other vehicals) have lung cancer risk increased by about a third. Some Swedish researchers estimated that as many as 1 in 10 lung cancers might be caused by air pollution in the Swedish capital, Stockholm. Another research paper put the figure at about 1 or 2 lung cancer cases in every 100 caused by outdoor air pollution.
Scarring from previous lung disease
Having had a disease that caused scarring in the lungs may be a risk factor for a type of lung cancer called adenocarcinoma of the lung. Tuberculosis (TB) can cause scar tissue to form in the lungs. But it's not clear whether this can directly lead to lung cancer.
A family history of lung cancer
Researchers are looking into the impact of family history on lung cancer. It is likely that there is at least one faulty lung cancer gene that can be passed down in families (inherited). If you have a first degree relative with lung cancer, your risk of lung cancer is doubled. It is very hard to sort out the facts here, because of the major role of smoking. Families of smokers will all be exposed to cigarette smoke and so have an increased risk of lung cancer whether they have inherited a faulty gene or not. A study called GELCAPS investigated the possibility of a lung cancer gene. Researchers took a blood sample from diagnosed patients and one from their partner (as long as they hadn't also been diagnosed with lung cancer). This trial has recruited all the people it needs and we are waiting for the results.
Past cancer treatment
There is some evidence that having had cancer treatment in the past might increase your risk of lung cancer. Researchers in Sweden looked at the medical records of 140,000 breast cancer patients. They found that there did seem to be an increased risk of lung cancer between 5 and 20 years after breast cancer treatment. They think this may be due to smoking after having had radiotherapy to the chest. Treatment for other types of cancer has also been linked to a slightly increased risk of lung cancer years later. People who have had treatment for Hodgkin's disease, some types of non Hodgkin's lymphoma or testicular cancer may have an increased risk of lung cancer. Do remember that having any of these cancers is a much greater risk to your health than the slight increase in cancer risk from treatment. It is most important to get the treatment you need at the time.
In some of this research, lung cancer risk seems to be increased even more in smokers. If you have had radiotherapy to your chest it is very important not to smoke because your lungs will be more sensitive.
Diet and lung cancer
Researchers have recently been looking into links between vitamins and lung cancer. Fresh fruit and vegetables are thought to help prevent cancer because they contain chemicals that can prevent cell damage, such as the anti oxidant vitamins A, C and E, flavenoids and other chemicals. But if you smoke, it's no good carrying on smoking and just eating a lot of fruit and veg as well. The most important thing by far is to stop smoking. Changing your diet won't reduce your risk of lung cancer much if you continue to smoke.
Researchers have looked into whether taking extra vitamin E and beta carotene may help stop smokers getting lung cancer. The body uses beta carotene to make vitamin A. Early results suggest that taking vitamin supplements does not help prevent lung cancer and may even have been harmful in smokers or those who have been exposed to asbestos in the past. Another substance, similar to beta carotene, called beta cryptoxanthin is found in fruits such as oranges and mangoes. It may lower lung cancer risk, but we don't yet know how it affects smokers. Having enough selenium in your diet may also help lower lung cancer risk, but the evidence isn't completely clear as researchers have measured selenium levels in different ways in different trials.
So, for now the advice on diet is the same as for preventing cancer generally and other chronic diseases. We should all try to
* Eat more fresh fruit and vegetables
* Cut down on fat (particularly animal fats)
* Eat less salt and sugar
* Cut down on alcohol
