Introduction
Lung cancer is the third most common cancer across Europe. Each year over 385,000 people are diagnosed with lung cancer. It is four times more common in men.
The two main types of lung cancer are non-small cell lung cancer (NSCLC), which represents approximately 80% of lung cancers and small cell lung cancer (SCLC), which accounts for the remainder.
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The Lungs
The lungs enable us to extract oxygen from the air and to get rid of waste carbon dioxide. Every breath we take draws over a litre of air into the lungs, through the mouth and trachea (windpipe). The trachea divides into two airways, the two main bronchi, one leading into each lung. The two main bronchi divide further to form smaller tubes (smaller bronchi and bronchioles) which deliver air to small air sacs (alveoli), where oxygen enters the bloodstream and carbon dioxide, a waste gas, is expelled.
The right and left lungs have a slightly different structure – the right lung has three lobes and the left lung has two, but they work in exactly the same way.
Lung cancers start in the cells lining the airways or bronchi and so are called carcinomas of the bronchus, or bronchogenic carcinomas.
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Lung Cancer
All cancers are uncontrolled growths of cells. In lung cancer this uncontrolled growth happens in the cells lining the inside of the bronchi – the tubes carrying air into the lungs. All types of lung cancer are caused by smoking or being exposed to other peoples’ cigarette smoking.
Different types of lung cancer can be identified. These are:
- Non-small cell lung cancer, which can also be divided into different types, although sometimes it can be difficult to tell them apart even when samples are examined under the microscope. The three types of non-small cell cancer are:
- Squamous cell carcinoma - the most common type of lung cancer, which tends to occur near the centre of the lungs.
- Adenocarcinoma - this develops from glands in the lungs which produce mucus. This tends to occur towards the outer part of the lungs. It is becoming more common.
- Large cell carcinoma or undifferentiated carcinoma - this consists of large, round cells.
- Small cell lung cancers (SCLC), made up as the name suggests of small round cells, constitute about 15% of all lung cancers, and non-small cell lung cancer (NSCLC) the remaining 80% of lung cancers.
- Mesothelioma is another type of cancer that affects the covering of the lungs (the pleura). It is relatively rare and usually occurs in people who have been exposed to asbestos.
These different lung cancers do not behave in the same way.
One of the characteristics of cancer is that it can spread to other parts of the body, either by directly invading neighbouring areas or because the cancer cells travel through the blood or lymphatic system to other parts of the body. Lung cancer may spread to surrounding structures such as the other lung, the ribs and chest wall, as well as through the blood stream to the bones, liver and other organs of the body.
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Lung Cancer Risk Factors
Cigarette smoking causes most lung cancers, but lung cancer can occasionally develop in non-smokers. The more you smoke and the longer you have been smoking, the greater the risk of developing lung cancer. Although filter and low-tar cigarettes carry a smaller risk of cancer than other types of cigarette, it is still much more dangerous than not smoking at all. Adenocarcinomas are more common in people who smoke these sorts of cigarette.
Lung cancer has always been more common in men, but that is just because men have tended to smoke more than women. Lung cancer is now becoming more common in women because more women now smoke.
If you stop smoking, the risk of developing lung cancer falls. After about 15 years, the risk of developing lung cancer falls back to that of a non-smoker.
Exposure to other people’s cigarette smoke is also dangerous as it also increases the risk of developing lung cancer.
And it is not just tobacco smoke that is dangerous - cannabis also increases the risk of lung cancer, probably causing similar damage to tobacco smoke.
Not everyone who smokes will develop lung cancer. Some people seem more likely to develop lung cancer and this may be due to genetic factors, but as yet no specific faulty genes have been identified.
People exposed to asbestos over a long period of time are more likely to develop lung cancer, especially if they smoke, and mesothelioma - a rare cancer of the membrane (the pleura) that covers the lungs - is specifically linked with exposure to asbestos fibres.
In some areas where granite and other igneous rocks are found, radon gas can be found in relatively high concentrations in the air, and this may increase the risk of lung cancer.
There is no certain method of eliminating the risk of lung cancer but stopping smoking will dramatically reduce the risk of developing lung cancer and will at the same time significantly reduce the risk of many other potentially fatal diseases.
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Preventing Lung Cancer
There is no certain way to prevent lung cancer but the fact that it is comparatively rare in non-smokers and that the risk of developing lung cancer decreases after stopping smoking speaks for itself.
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Symptoms of Lung Cancer
The classic symptoms of lung cancer are:
- coughing up blood
- a persistent cough
- shortness of breath
- wheezing
- a hoarse voice
- chest and shoulder pain
- tiredness
- weight loss
These symptoms may be due to a variety of conditions. Lung cancer is one possible cause, but anyone who has these symptoms for more than 3 weeks should seek medical advice quickly.
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Diagnosing Lung Cancer
There is no screening test for lung cancer at present, but there are a number of tests that can help in the diagnosis of lung cancer which include:
- Chest X-ray – lung cancer often shows up as a shadow on chest X-rays. This may be the first indication in patients with no symptoms at all. A chest X-ray never provides a certain diagnosis and additional tests are required.
- Sputum examination – Cancer cells can be present in sputum, so sputum samples can be examined to look for these cells.
- Computerised tomography (CT scan) is a type of X-ray. It uses beams from several different angles, building up a picture of all the body tissues it passes through. The result is a series of pictures showing the shape of the body organs in cross section. A series of these pictures allows experts to say whether there are any abnormalities present.
- Positron emission tomography (PET scan), uses small amounts of radioactive material to detect cancer and other diseases in the body. Different radioactive materials are given as an injection or a drink. Once in the body, the material concentrates in certain tissues giving off focal radiation which can be detected by the scanner to produce visual images. Experts can then use these images to help make a diagnosis.
- Bronchoscopy – by passing a thin flexible telescope through your nose or mouth and into the lung airways your doctor can look directly into your lungs, taking photographs and samples. These samples can then be examined under the microscope to provide a clear diagnosis.
- Lung biopsy – a sample of lung tissue is obtained by passing a needle through the skin into the part of the lung where something abnormal has been found on X-ray. The needle is guided into position using X-rays showing on an image screen. A sample of cells is taken for examination under a microscope in the laboratory.
- Mediastinoscopy – under anaesthetic, a small cut is made in the notch above the breastbone and a tube passed into the chest. Through the tube your doctor can look directly at the centre of the chest and take samples for examination under a microscope.
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Treating Lung Cancer
There are a number of treatments for lung cancer, and more than one option may be appropriate or possible for an individual patient. Treatment options are usually discussed by a team of specialists including respiratory (lung) physicians, radiologists, chest surgeons, and specialists in chemotherapy and/or radiotherapy. But the final decision on treatment always rests with the patient.
Surgery
Non-small cell lung cancers that have not spread to nearby lymph nodes in the centre of the chest, and have not spread to other parts of the body can be treated using surgery. Surgeons may remove a small part of one lung, often one lobe of the lung (lobectomy), or the entire lung (pneumonectomy). Surgery may become an option for some patients after radiotherapy or chemotherapy or both have reduced the size of the cancer.
Because small cell lung cancers (SCLC) are rarely found in just one place, surgery is not usually a good option. For these tumours chemotherapy, radiotherapy or both treatments in combination are better forms of treatment.
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Radiotherapy
Radiotherapy options include external beam treatment and to a lesser extent brachytherapy.
External beam radiotherapy uses high energy X-ray beams generated from machines to kill cancer cells. Some normal cells will also be affected, but the treatment is planned so that the radiation is focused on the affected areas from a variety of different angles, so normal tissues receive a smaller dose. Normal cells are better at repairing themselves than cancer cells.
External beam radiotherapy is normally given as a series of short regular treatments in a radiotherapy department (each treatment may be referred to as a fraction) over a period of several weeks. Treatments for reducing symptoms (palliative treatments) may be given over much shorter periods.
All radiotherapy treatment is delivered to an area that is as near as possible to the shape of the cancer, so a higher dose of radiation can be more precisely targeted at the cancer avoiding neighbouring healthy tissue and resulting in fewer side effects.
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Stereotactic radiotherapy (SRT)
Stereotactic radiotherapy is a form of high-precision radiotherapy that is now becoming available in many centres. SRT provides radiotherapy focused on the whole tumour, with very little effect on surrounding normal tissues. This allows the use of very high doses of radiation in 3-8 treatment sessions or fractions over a two week period. During SRT, patients are positioned very precisely during treatment to minimise radiation of nearby normal tissues. SRT also includes measures to allow for movement of the cancer during imaging and treatment planning as well as during radiotherapy.
Radiotherapy can be used as the main treatment for lung cancer or to help to relieve some of the symptoms such as shortness of breath. As an alternative to surgery, radiotherapy may be given alone or combined with chemotherapy. When given at the same time, the combined effect of radiotherapy and chemotherapy together is more effective than when given separately. It is particularly useful for patients for whom surgery is inappropriate or would carry high risks.
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Treatments given inside the Lungs (Endo-bronchial Treatments)
Specific symptoms such as breathlessness caused by obstruction of the trachea (windpipe) or one of the main airways can be relieved using laser beams.
Lasers are powerful light beams that can be used to burn lung cancers that are blocking the larger airways and so causing symptoms like wheezing and breathlessness.
The laser is positioned using a bronchoscope. When it is turned on, the laser is focused on the cancer and as much as possible is burnt away. Treatments can be repeated as often as necessary.
Brachytherapy can also be used to treat some of the complications of lung cancer. It delivers radiotherapy directly to the cancer site, minimising damage to healthy lung tissue. Brachytherapy is particularly effective in stopping bleeding from tumours and opening up blocked areas of the lung, but in many centres laser treatments are now used instead.
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Chemotherapy
This is a very important treatment for lung cancer - drug treatments to kill cancer cells can be used alone, or in combination with surgery and/or radiotherapy.
The drugs used most commonly to treat lung cancer are cisplatin, carboplatin, gemcitabine, vinorelbine, paclitaxel and docetaxel. Two or three of these drugs are usually given at the same time, as clinical trials have shown that they have more effect this way. Clinical trials are the way that improvements in treatment are tested.
Some drugs are given by injection, but others are tablets. Drugs are given in cycles, which may last a few days, followed by a rest period of a few weeks. This allows your body to recover from the side effects of treatment.
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Looking after Yourself
Treatments for lung cancer, like all others, cause some side effects. Many of these can usually be treated effectively, so if you experience problems it is important to mention them to your doctor or nurse, so they can give you the treatment you need.
Possible side effects of radiotherapy for lung cancer depend on what part of the lungs is being treated and what other structures are nearby.
A sore throat and trouble with swallowing can occur if the central part of the chest is being treated. These symptoms tend to start 2 to 3 weeks into treatment, but sooner if chemotherapy and radiotherapy are given together. Warm drinks are easier to swallow than very hot or cold, and a soft diet like soups, mashed potato and scrambled eggs is easier during the few weeks that symptoms persist. Dieticians will be able to provide much more advice, and there are some medications that are helpful.
A cough is common during or after radiotherapy, sometimes with phlegm (mucus) to bring up. Cough medicines can help to some extent but are unlikely to stop the cough altogether and if there is phlegm present it is important to cough it up to prevent a chest infection. Your physiotherapist will also be able to help as well. The cough should stop after treatment. If you feel feverish or unwell you may need antibiotics, so it is important to tell your doctor straightaway.
Hair loss in the treated area is temporary, as the hair usually grows back within a few months.
Pain in the chest can occur within 24 hours of starting treatment and usually goes away. It can be helped by painkillers, but if it is severe or persists tell your doctor.
Skin irritation in the area being treated can happen, but usually just with treatment for certain types of lung cancer, for example, a Pancoast tumour. Limiting the amount you wash the affected area, washing just with plain water, and avoiding perfumed soap will all help. Aqueous cream as a moisturiser and a weak hydrocortisone cream also help.
Whatever the problem, do not assume that nothing can be done about it – ask your doctor or nurse: do not just grin and bear it.
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Questions for Your Doctor
Before making up your mind about the best treatment option for you, you will need information about your cancer, the treatments available in your area and what this will involve, what to expect from the treatment, what side effects you might experience and how these may change over time as well as what your doctors believe would be most effective in combating your cancer.
For different patients the answers will be different, so it is important to discuss all these issues with your doctor so that you make the right choice for you.
You will have your own questions but some issues you might want to raise are:
- What does the treatment involve?
- What are the benefits I might get?
- How good are my chances of getting those benefits?
- Could having treatment make me feel worse? If so, in what way?
- Are there alternative treatments?
- What are the risks of the treatment?
- Are the risks minor or serious? How likely are they to happen?
- What care will I need after treatment?
- What happens if something goes wrong?
- What may happen if I don’t have the treatment?
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Conclusion
There is no one solution to the management of lung cancer, but for clinical and personal reasons particular treatments will suit some patients better than others. Patients therefore need comprehensive information so that they can make the right decision for them.
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