Selasa, 01 Januari 2008
SMOKING TO MUCH ...CAUSE LUNG CANCER, SO STOP FROM NOW
Reviewed by Dr Gavin Petrie, consultant chest physician
What is lung cancer?
Lung cancer is one of the largest killers in the Western world. The risk of developing lung cancer is increased 10-40 times if you smoke.
The cells of all living organisms normally divide and grow in a controlled manner. Cancer results when this control process is lost. A lump or tumour, known as the primary tumour can grow locally or spread to produce secondary tumours somewhere else in the body. This spreading process is called metastasis.
About 40,000 people in the UK die every year from lung cancer. It is the most common form of cancer in the UK and the most common cause of death from cancer in both men and women although it affects more men than women.
What causes lung cancer?
Tobacco smoke is the primary cause of lung cancer. Although nonsmokers can get lung cancer, the risk is about 10 times greater for smokers and is also increased by the number of cigarettes smoked per day.
If you are a heavy smoker consuming more than 20 cigarettes a day, the risk of developing lung cancer is about 30 to 40 times higher than if you don't smoke.
The main reason for the substantial increase in the disease over the last 50 years has been the increase in the number of people who smoke cigarettes. This has resulted from the industrial production and marketing of tobacco.
The risk of lung cancer in an ex-smoker falls to the same level as a nonsmoker after about 15 years.
What are the symptoms of lung cancer?
The symptoms of lung cancer include:
* a chronic cough.
* worsening breathlessness.
* weight loss.
* excessive fatigue.
* persistent pain in the chest or elsewhere, (possibly from the cancer spreading to a bone).
* symptoms can be due to the original tumour in the lung or to the effects of secondary tumours elsewhere in the body.
* one of the most significant symptoms of lung cancer is coughing up blood or haemoptysis. This can sometimes occur as an early warning sign of a cancer which may still be curable. Any person who coughs up blood should see their GP for advice urgently as lung cancer must be considered, particularly if the person is a smoker over the age of 40.
How is lung cancer diagnosed?
Sadly, most lung cancer is diagnosed too late for curative treatment to be possible. In over half of people with lung cancer the disease has already spread (metastasised) at the time of diagnosis.
Early diagnosis is difficult because many of the common symptoms of lung cancer are similar to those of smokers' lung (chronic obstructive pulmonary disease or COPD).
In addition to this, most lung cancer patients will also have COPD because both conditions are mainly caused by smoking. However, only 1 or 2 per cent of COPD patients will go on to develop lung cancer.
The first investigation is a chest X-ray. If a lung tumour is present, it needs to be at least a centimetre in diameter to be detectable by an ordinary X-ray. However, by the time a tumour has reached this size the original cell which became cancerous has divided (or doubled) 36 times. As death usually results after 40 such cell divisions, it is clear that lung cancer is a disease that is usually detected late in its natural course.
Some simple blood tests and further examinations may also be carried out.
Bronchoscopy is direct inspection of the inside of the breathing tubes with a thin fibre-optic instrument using local anaesthetic and is the best test for tumours in the main bronchi (air passages) in the centre of the chest.
Depending on the site of the cancer, a biopsy will be obtained either by a bronchoscopy or a needle biopsy. Needle biopsy is better for cancers near the periphery of the lungs (ie closer to the ribs than the centre of the chest), beyond the reach of the bronchoscope.
Usually, a sample of sputum - the material coughed up from the respiratory tract - will also be examined for cancer cells and this can avoid the need for biopsy.
A CT scan provides more information about how much the tumour may have spread.
There are three main types of lung cancer, based on their appearance when examined under the microscope by a pathologist:
* small cell carcinoma
* squamous cell carcinoma
It is important to know which type of cancer a patient has because small cell cancers respond best to chemotherapy (anti-cancer medicines) whereas the other types (often referred to collectively as non-small cell cancer) are better treated with surgery or radiotherapy (X-ray treatment). The pathologist therefore needs a small tissue sample (biopsy) to examine. This will confirm that the diagnosis of suspected cancer is definitely correct and show which type of cell is involved.
How is lung cancer treated?
Surgery can cure lung cancer, but only one in five patients are suitable for this treatment. If the tumour has not spread outside the chest and does not involve vital structures such as the liver, then surgical removal may be possible, but only if the patient does not also have severe bronchitis, heart disease or other illnesses. These additional complications put too great a strain on the patient for them to be able to stand surgery.
Small cell lung cancer is treated with chemotherapy. This is given either by an oncologist (a specialist in cancer treatment) or sometimes by a physician in chest diseases with special experience in chemotherapy. It is given in courses which means that the patient has to stay in hospital for about 48 hours approximately every three weeks.
Popular misconceptions about chemotherapy are common and there is often concern about its perceived difficulties and usefulness. However, there is no doubt that chemotherapy is effective and that it both prolongs and improves the quality of survival in small cell lung cancer. The number of courses required will depend on how well the individual patient responds.
Chemotherapy does have side effects, particularly nausea, vomiting and hair loss. However there are very good drugs to control these side effects. Hair always grows again about three months after the chemotherapy courses have finished.
There is scope for improving the results of chemotherapy and many research trials are going on. Patients who are asked for their consent to take part in a trial should not be frightened. Hundreds of patients take part in trials to detect any benefit between one treatment regime and another. This research must be done if cancer chemotherapy can continue to improve.
Non-small cell cancer may be treated with radiotherapy, chemotherapy (as part of a research trial), or with supportive care.
Radiotherapy is either 'radical' or 'palliative'. Radical is used in selected patients with localised tumours who are inoperable, and involves using high doses of radiation.
Palliative radiotherapy is widely used. It involves using lower doses of radiation - often in just one or two doses. It is very good for relieving symptoms, such as blood in the sputum (haemoptysis), bone pain, and also for helping obstruction to the airway or large veins in the chest.
What is the outlook?
About 10 per cent of patients can expect to be 'cured' - that is alive five years after diagnosis with no evidence of the cancer having returned.
However, all patients can benefit from palliative treatment which can improve the quality of survival.
The main improvement in the management of lung cancer in recent years relates to the palliative care services with an increased emphasis on symptom control and support to the family.
The course of lung cancer may be brutally short. In the UK, MacMillan Cancer Relief charity, the Hospice movement, the family doctor and their team provide invaluable support and information to patients and families affected by cancer.
Based on a text by Dr Per Grinsted, GP