The lungs are located in the chest and enable us to breathe. When we breathe in, air goes through our nose, down our windpipe (trachea), and into the lungs, where it spreads through tubes called bronchi. Oxygen from the air that we breathe can then pass into the blood and to the rest of the body to allow the body to function normally.
Lung cancer refers to the uncontrolled growth of abnormal cells which come from the lungs, usually from the cells that line the bronchi. The abnormal cells do not carry out the function of normal lung cells. As these abnormal cells grow, they can get bigger and start to interfere with the normal functioning of the lung. They can pass from the original part of the lung to other parts of the body, such as the opposite lung, our lymph nodes, bones, liver etc.
The two main types of lung cancer are:
Small cell lung cancer is more rapidly growing and spreads earlier to other organs as compared to non-small cell lung cancer. Non-small cell lung cancer generally grows slower than small cell lung cancer and tends to be confined to the lung for a longer period of time.
Once cancer is diagnosed, further scans of the bones, brain and rest of the body may be performed to determine if the cancer has spread to other organs. The results will be reviewed by the doctor to determine the final stage of the lung cancer.
Lung cancer is the number 3 killer in males and females in Singapore. Between 2014 and 2018, an average of 1,589 people in Singapore were diagnosed with lung cancer yearly.
Most people diagnosed with lung cancer are above 40 years old. However, the disease may begin before this age range.
Often, there may be no symptoms of lung cancer, particularly when it is at an early stage. However, common symptoms of lung cancer include:
Avoid active and secondary tobacco smoke exposure.
Cigarette smoking is the main cause of lung cancer. The risk of lung cancer developing in a smoker is 15-25 times more than for a non-smoker. The risk of lung cancer is greater with increasing number of years of smoking and with higher number of cigarettes smoked per day. Pipe, cigar and marijuana smoking also increase the risk of lung cancer. Breathing in the smoke of others (called second hand smoke) can increase the risk of developing lung cancer by about 30%. The risk to children of smokers is not yet accurately quantified.
Exposure to certain workplace chemicals such as asbestos, coal gas, chromium, nickel, arsenic, vinyl chloride, and mustard gas may also increase the risk of lung cancer.
Despite the strong association of smoking with lung cancer, it has also been recognised that more than one-quarter of lung cancer cases in Singapore occur in people who have never smoked, and who do not have prior smoke exposure.
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 will then be performed and 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, or if the chest x-ray shows any abnormality, a special scan of the lungs, called a CT (computed tomography) scan may be performed to evaluate more accurately for presence of lung cancer. If this scan shows a suspicious mass, a biopsy may be recommended, where a small specimen from this mass is then obtained for examination under a microscope, to look for the presence of cancer cells.
In lung cancer, this biopsy can often be performed in a few different ways, such as passing a needle through the skin into the lung mass under X-ray guidance, or by performing a bronchoscopy examination, where a small tube is introduced through the mouth and into the lung. Small specimens from the suspicious lung mass can be removed for further examination. Alternatively, a biopsy sample may also be taken from the lymph nodes or other areas that the cancer has affected, such as the liver.
After the diagnosis, further genetic tests may be performed on the cancer cells from the biopsy sample, which may help doctors decide which a suitable treatment for the cancer.
Lung function tests may be performed to determine how well the lungs are working and determine if it is safe to proceed with treatments such as surgery or radiotherapy to the lungs.
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 scans of the brain are also required.
A lung function test, which involves blowing into a large cylinder, may be performed pre-operatively to determine the lung function prior to any surgery discussions.
Chemotherapy is essential in the treatment of small cell lung cancer, due to its tendency to spread early to other organs, such as liver, bone and brain. If the cancer is still localised to one part of the lung and within the lymph nodes of the lung, radiotherapy to the lungs is administered together with chemotherapy. This combination of chemo-radiotherapy has been shown to have better results than just chemotherapy alone for patients with localised cancer. Surgery is usually not recommended for small cell lung cancer. The exact choice of chemotherapy medicine will depend on the person's general health and other prevalent medical problems.
Surgery, radiotherapy, chemotherapy and targeted therapy alone or in combination may be used to treat NSLC. In general, stage I and stage II cancer, where the cancer is localised to one part of the lung only, is usually treated with surgery to remove the lung cancer. Sometimes after surgery, further chemotherapy may be recommended to reduce the change of the cancer from returning.
For patients with stage III lung cancer, where the cancer may be large (>7cm), or have spread to the lymph nodes between both lungs, a combination of chemotherapy and radiotherapy to the lungs may be recommended.
For stage IV lung cancer, where the lung cancer cells have spread to other parts of the lungs and/ or body, further tests of the biopsy specimen to subtype the cancer further may help determine whether chemotherapy or targeted therapy with specific tablets will be more suitable.
Prognosis means the probable outcome of an illness based upon all the relevant facts of the case. The results of patients' clinical examinations, X-ray investigations and biopsy reports are considered together in order to decide what the stage and 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.
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