Lung cancer is the most commonly diagnosed cancer in the world. In the UK, it's the second most-frequently occurring cancer, accounting for one in seven new cases.
Dr Trisha Macnairt medically reviewed this article in April 2009
What is lung cancer?
There are several different types of lung cancer, which are generally divided into:
- Non-small cell lung cancer (NSCLC)
- Small cell lung cancer (SCLC)
Nine out of 10 cases of are caused by the effects of tobacco smoking - and unfortunately the majority of cases cannot be cured.
Lung cancer symptoms
The key symptom of lung cancer is a persistent cough that gradually gets worse.
If you have the following, or any other symptoms, you must have them checked by your doctor (but remember, all occur in many conditions other than cancer):
- A persistent cough or change in the nature of a long-standing cough
- Shortness of breath
- Coughing up blood-stained phlegm (sputum); blood is a warning sign that always needs urgent investigation
- Persistent chest pain - a dull ache or sharp pain when you cough or take a deep breath
- Loss of appetite and weight
- A drop in ability to exercise and general fatigue
At present, there's no effective screening test for lung cancer. If you have any worrying or new symptoms, tell your GP straight away so you can be investigated promptly or reassured that there's nothing to worry about.
Lung cancer causes
As most lung cancer cases are caused by smoking cigarettes, the risk increases with the number and type of cigarettes smoked. Even passive smoking (inhalation of other people's cigarette smoke) can cause a problem, and the longer period over which the patient smokes, the higher the risks. Only one in 10 lung cancers occurs in non-smokers. Pipe and cigar smokers have a lower risk than cigarette smokers, but it's still a far greater risk than that of a non-smoker.
Some people seem to be genetically predisposed to developing lung cancer, and medical checks in smokers may in future look for these key genes to work out how likely lung cancer is.
Some rare types of lung cancer aren't related to smoking. Mesothelioma, which affects the covering of the lung (the pleura), for example, is almost always caused by exposure to asbestos. Other causes include exposure to certain chemicals and substances in the workplace, such as uranium, chromium and nickel. These have all been linked to lung cancer but are very rare. Contact your local environmental health officer if you're concerned.
If a person stops smoking the risk of lung cancer is greatly reduced, so that after about 15 years the chances of developing the disease are similar to that of someone who has never smoked.
Lung cancer has always been more common in men, particularly those aged over 40. However, as fewer men smoke now rates have fallen. Meanwhile lung cancer rates increased among women until the 1980s as more took up smoking. Although rates among women have stabilised, the disease now claims more lives than breast cancer.
Diagnosing lung cancer
There are several tests to diagnose lung cancer. These include:
- CT or MRI scans – these sophisticated scans involve lying still inside a machine as it takes images of the internal organs. The pictures that result can give a very good idea of whether cancer might be present but aren't absolutely definite as cell samples are needed to make a full diagnosis. Scans are often done in order to guide a biopsy to suspicious areas.
- Bronchoscopy - a thin flexible tube is passed gently through your nose or mouth and into the lung airways. Photographs and cell samples are then taken
- Mediastinoscopy - a small cut is made in through the skin at the base of the neck under general anaesthetic just above the breastbone or on the left side of the chest next to the breastbone. Then a thin flexible telescope (mediastinoscope), often with a grabbing device attached down the airways of your lungs, is then passed into the chest, allowing the doctor to examine the area at the centre of the chest and local lymph nodes a small cut is made.
- Lung biopsy - a needle is passed through the skin into the lung and a sample of cells is taken for examination.
Lung cancer treatments
Treatment of lung cancer depends on the type of tumour, its location and how far it has spread, as well as the persons general health. A process known as staging is used in each case to asses these factors and recommend appropriate treatment, which may include surgery, chemotherapy andradiotherapy. Lung cancer patients may be referred to special clinics.When the tumour is away from the centre of the chest and there's little or no spread (typically in NSCLC), surgery is often used. A small part of the lung may be removed, or the entire lung.You can breathe normally with only one lung. However, if you had breathing difficulties before the operation you may be more breathless afterwards. Breathing tests will be carried out to help you and your doctor decide on the best course of action.Chemotherapy and radiotherapy will be considered in many cases. Unfortunately, NSCLC is hard to cure, and in many cases, the treatment given will be to prolong life as far as possible - and relieve symptoms. SCLC is different, in particular, it has a tendency to spread to distant parts of the body at a relatively early stage. Chemotherapy and/or radiotherapy are usually more effective in treating this type because it usually spreads to more than one place by the time it's diagnosed and is less likely to be cured by surgery.In some cases laser therapy can provide some relief and new treatments are also being studied and starting to come into wider use, including biological therapies which are drugs that block the signals that cancer cells need to grow. In NSCLC, different ways of giving radiotherapy and chemotherapy are being investigated.Sometimes new symptoms can develop, which may be caused by the spread of the cancer to other parts of the body, but could also come about because some lung cancer cells produce hormones that upset the body's chemical balance.
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