What is lung cancer?

Lung with enlarged alveoli diagram:

Lung cancer develops when cells become abnormal and grow out of control. Over time they form a clump - also known as a tumour. Lung cancer develops in the tubes that carry air in and out of the lungs (your airways). It can grow within the lung, and it can spread outside the lung.

Lung cancer often develops slowly. It is thought that cells first become abnormal at least five years before the cancer can be detected. The reasons for this delay include:

* most tumours grow slowly
* the lungs are large
* the lungs do not feel pain (pain is not common in lung cancer)
* some of the symptoms are similar to those of COPD, which many smokers also have.

The result of this is that by the time lung cancer is diagnosed, it has often spread outside the lung. If this happens, the cancer is not curable.

There are two main types of lung cancer, called

* small cell cancer
* non small cell cancer; this includes ‘squamous’ cell cancers and ‘adenocarcinoma’.

Who is at risk?

Anyone can develop lung cancer, but people who smoke (or used to smoke) are most at risk. The risk increases with the total number of cigarettes you smoke. If you stop smoking, the risk gets less over time.

Passive smoking over a long period of time may occasionally cause lung cancer.

Non smokers may also develop one particular type of lung cancer ("adeno"). This can happen in a part of the lung where there is scarring because of something else.

Researchers are trying to find out if there is a genetic reason why only some smokers get lung cancer. There is no clear answer yet.

What are the symptoms?

Common symptoms are:

* a cough that won't go away. This is caused by irritation of the tubes that carry air in and out of your lungs (the airways)
* breathlessness - if the tumour is either large or blocks off an airway
* wheezing from that side of the chest - this may make it difficult to sleep on one side
* blood in your sputum (phlegm)
* pain - usually only if the tumour reaches the edge of the lung
* weight loss - because cancers use up energy to grow.

If you have these symptoms, you should see your doctor. But these symptoms are also very common in people who do not have lung cancer. People with long-term lung disease may have many of these symptoms in any case. A clue to possible lung cancer is if usual symptoms change or become worse. Your doctor will arrange for tests to know whether or not you have lung cancer.

In a few cases where the tumour has spread outside the lungs, the first symptom may not come from the chest at all, for example:

* liver jaundice (when the colour of your skin or eyes becomes yellow)
* bone pain or fracture
* skin lump
* nerve or brain damage affecting walking, talking, behaviour or memory.

How is lung cancer diagnosed?

By the time symptoms appear, the tumour can nearly always be seen on a chest X-ray. This test is easy for family doctors to arrange and it is safe. If lung cancer seems likely then you will be seen by a hospital chest specialist within two weeks.

The specialist may need to take a sample of tissue (called a "biopsy"). There are different ways of taking a biopsy:

* if your tumour is near the middle of your lung, the chest specialist will use a bronchoscope. This is a very small telescope, and the test is done under sedation, so you won't feel anything
* if your tumour is near the edge of your lung, an X-ray specialist ("radiologist") will pass a needle into your chest, using a local anaesthetic to numb the area
* occasionally it is necessary to perform a minor operation under general anaesthetic to be sure of getting a good specimen.

You may also be advised to have a scan called a CT scan. This provides information about:

* the lung tumour in more detail
* exactly where and how big it is
* whether the cancer has spread outside your chest
* which sort of biopsy would be most helpful.

A CT scan involves lying on a cushioned table which moves through a large metal hoop. Some people worry that it will feel claustrophobic, but the staff will explain the procedure and talk to you during the test. You will be given an injection in your hand, and the machine will take pictures of your chest and stomach area. The whole procedure only takes a few minutes.

NB: it may take a few days for your test results to come through. Make sure you have a follow-up appointment.

Getting your results

Once the specialist has your biopsy and CT scan results, she/he will discuss them with a group of lung cancer specialists who will work out what type of lung cancer you have and what treatment option is best for you. They will take into account:

* the type of lung cancer
* how developed it is (called the "stage" it is at)
* your general health and symptoms

Although you will be offered the particular approach that seems best for you as an individual, you may wish to make up your mind after talking to your close relatives or family doctor. Of course, at all stages the doctors and nurses will respect the views that you have about your treatment.

You will probably have all kinds of questions you want to ask, such as:

* will I be cured?
* what are the side-effects of treatment?
* should I stop working?
* can I still go on holiday?
* am I going to die?

No-one will have all the answers, but the specialist will answer your questions as honestly as possible. You will be introduced to your specialist lung cancer nurse, who will give you a contact telephone number so that you can call to ask questions as they come up. You should find him/her very approachable and willing to give advice on the disease, your treatment and any symptoms or problems that the illness might be causing you.

Unfortunately most people with lung cancer cannot be cured, and the illness may eventually lead to death. Energy and appetite get less, and normal activities become an effort. When these happen, life expectancy may only be a few weeks.