Lung Cancer
What is Lung Cancer?
The air we breathe enters the lungs through the trachea and then into the right and left bronchi. The bronchi are airways which branch into smaller and smaller airways until it becomes an air sac. Oxygen is absorbed and carbon dioxide expelled via the air sacs.
The average lung has more than 300 million of these air sacs. Mucus produced by the air sacs trap any foreign material which enter the airway. Tiny hair-like structures called cilia sweep the mucus out of the lungs and into the throat where the mucus and foreign material is coughed out or swallowed.
Constant insult to the cells of the airways, such as smoking, will cause an increased production of mucus which has to be coughed out. The cilia become worn out from constant trapping of the foreign material, i.e. the particles which come from cigarette smoking, and mucus stays in the airways and air sacs. The air sacs may be destroyed. Even if cancer does not develop, smoking causes severe lung damage which may cause signs and symptoms which mimic lung cancer.
Cancer usually starts in the cells lining the larger airways. Eventually, cancer cells may spread to neighbouring lymph glands and elsewhere.
How common is Lung Cancer?
Lung cancer is the commonest cancer in many countries. Between 1993 and 1997, there were over 4, 601 people in Singapore diagnosed to have lung cancer. The great majority were smokers. The risk of lung cancer in a smoker is 15 to 25 times more than for a nonsmoker.
Age of Onset
Most persons diagnosed with lung cancer are older than 40 years of age. However, the disease may begin long before this.
Risks and Causes
Cigarette smoking is the main cause of lung cancer. It is responsible for > 90% of lungs cancers. With increasing number of years of smoking and the number of cigarettes smoked per day, the risk of cancer increases. Pipe and cigar smoking and marijuana smoking also increase the risk of lung cancer. Spouses of smokers have a 35% higher risk of developing lung cancer compared to spouses of non smoking persons, the risk to children of smokers is not yet accurately qualified.
Exposure to certain workplace chemicals such as asbestos, coal gas, chromium, nickel, arsenic, vinyl chloride, and mustard gas increases the risk of lung cancer.
Symptoms and Signs of Lung Cancer
Cigarette smoking causes lung damage even in the absence of cancer. The symptoms associated with lung damage are cough and shortness of breath. There may be occasions when there is production of blood stained sputum even when there is no cancer. Lung infections are also common in persons with lung damage. Dilatation of the air Spaces, or emphysema, is reported to be an especially common complication of smoking in chinese. Lung cancer usually develops in the presence of lung damage. The symptoms and signs of lung cancer may be indistinguishable from lung damage caused by cigarette smoking. Occasionally, lung cancer is diagnosed incidentally when a pre-employment or routine chest x-ray is performed.
Diagnostic Tests
Any persistent cough or change in the nature of the cough, the appearance of blood-stained sputum, or unexplained breathlessness should prompt a person to seek medical advice. Often chest x-rays are important in the first diagnosis of lung cancer. Sputum may be sent for testing for cancer cells or infections, such as tuberculosis which is not uncommon in Singapore.
If the suspicion of cancer is high, a bronchoscopy may be arranged. In this examination, a fiber-optic tube about 7 millimeter in diameter, is introduced through the nose and into the lung under light-sedation and local anaesthesia. You will be able to breath normally during the procedure which lasts 15 to 30 minutes. Small pieces of tissue can be painlessly removed for further examination to diagnose cancer.
Once cancer is diagnosed, computerised tomography (CT) scans of the chest and liver may be performed to determine if the cancer has spread to other organs, such as the liver or adrenal gland, which is just above the kidneys on both sides. Occasionally, bone scans and CT of the brain are also required.
A lung function test, which involves blowing into a large cylinder,may be performed preopentively to determine the lung function prior to any surgery discussions.
Treatment of Lung Cancer
There are two main types of lung cancer, small cell lung cancer and non-small cell lung cancer. The diagnosis is based on what the pathologist (specialist who looks at tissues under the microscope) sees on microscopic examination of the tissue removed and after special staining tests have been performed on the tissue.
Small cell lung cancer is more rapidly growing and spreads earlier to other organs than non-small cell lung cancer. About 10% of all lung cancers are small cell lung cancer. Non-small cell lung cancer grows slower than small cell lung cancer and tends to be confined to the lung for a longer period of time.
Treatment of Non-small cell Lung Cancer
Surgery is the treatment of choice. The cancer and part of the surrounding normal lung is removed together with neighbouring lymph nodes. Radiotherapy after surgery may be necessary if it is felt that there may be cancer cells left in the remaining lung tissue which may cause the cancer to recur at a subsequent date, i.e. local recurrence attentively, it is given if mediastined lymph nodes are involved by tumour. Radiotherapy usually takes place over 5 to 6 weeks and causes minimal temporary side-effects.
If surgery is considered too risky because of the person's other medical conditions, radiotherapy may be given to the cancer and the neighbouring lymph nodes. The exact amount of radiation given has to be decided on an individual basis by the radiation oncologist (specialist in radiotherapy). Many factors have to be taken into account, such as the person's age, general health, amount of normal lung, size of cancer. Alternately, it is given if mediastinal lymph nodes are involed by tumour. Radiotherapy may be combined with chemotherapy.
Sometimes chemotherapy is given first in order to shrink the lung cancer before considering radiotherapy or surgery. This is usually the case if the cancer was large and considered technically difficult to remove by surgery or if the person has other medical problems making surgery too risky. This approach is usually decided after all specialists involved, the surgeon, medical and radiation oncologists, have discussed the individual case.
Treatment of Small Cell Lung Cancer
Small cell lung cancer tends to spread early to other organs, such as liver, bone and brain. Therapy involves early chemotherapy. If the cancer has not spread beyond the confines of one lung, chemotherapy combined with radiotherapy has been shown to have better results than just chemotherapy alone.
Chemotherapy is given over 4 to 6 months. There is usually mild nausea or vomiting, complete hair loss, lethargy or tiredness, and loss of appetite. The exact choice of medicines will depend on the person's general health and other medical problems.
Prognosis of Lung Cancer
Prognosis means the probable outcome of an illness based upon all the relevant facts of the case. All findings from clinical examination and x-ray investigations and pathology reports are important and must be considered together to decide what the progress of an individual case of lung cancer may be. From this, the appropriate course of treatment can be decided and put into action. The treatment strategy will vary from person to person.
The doctor looks for the following features:
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The size of the lung cancer is important. The larger the cancer, the more likely the cancer will be inoperable. |
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Which of the neighbouring lymph glands were involved? Were all the involved lymph glands removed at surgery? |
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Did the pathologist see high risk features such as small cell lung cancer? Small cell lung cancer is a rapidly growing cancer. Very often, the cancer has spread to many other organs at the time of diagnosis. |
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Were other organs involved? |
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If the person has other underlying medical problems, surgery may not be possible even if the cancer was small and considered to be early stage. Lung cancer commonly develops in smokers who have lung damage from their many years of smoking. Smoking also increases a person's risk of heart disease and stroke, which may mean that surgery will be high risk. |
Frequently Asked Questions about Lung Cancer
1. I have been smoking for many years? Why should I stop smoking now?
Lung cancer takes years to develop. The risk increases with each increasing year of smoking, and with each cigarette smoked per day. Stopping smoking will reduce the risk of cancer developing. Smoking also increases the risk of other disease, such as bladder and cervix cancer, heart disease and stroke. Even without disease, smoking causes lung damage which may lead to symptoms such as chronic cough, and breathlessness. Smoking can also harm your spouse and family members.
2. How do I stop smoking? How do I stop a family member from smoking?
Smoking cessation clinics are available at many family practitioner's and polyclinics. Avail yourselves to any of these clinics. Giving a family member support will also help him or her to stop smoking. The Quit Programme has a self-help booklet that will also assist you.
Prevention:
Avoid active and secondary tobacco smoke exposure. Screening can help to detect lung cancer .
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