Lung cancer originates from tissues of the lung, usually from cells lining the air passages. The two main types are small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). These types are diagnosed based on how the cells look under a microscope. More than 80% of all lung cancers belong to the non-small cell type. The 3 major sub-types of non-small cell lung cancer are adenocarcinoma, squamous cell carcinoma and large cell carcinoma.
Lung cancer is the second most common cancer in men and the third most common cancer in women in Singapore. Men have a 3 times higher risk of lung cancer than women. Among the three major ethnic groups, the Chinese have the highest risk, followed by the Malays and Indians.
There are two main types of lung cancer:
Non-small cell lung cancer (NSCLC)
NSCLC is the more common type of lung cancer, and is less aggressive than SCLC. NSCLC tends to grow and spread more slowly. If discovered early, surgery and/or radiation therapy, chemotherapy may offer a chance of cure.
Small cell lung cancer (SCLC)
SCLC is fast-growing and rapidly spreads to the bloodstream and other parts of the body. Often, it is an advanced disease when diagnosed. It is usually treated with chemotherapy and not surgery.
What Causes Lung Cancer?
Doctors cannot always explain why one person develops lung cancer and another does not. However, we do know that a person with certain risk factors may be more likely than others to develop lung cancer.
Tobacco smoke is by far the most important and the main risk factor for lung cancer. It is responsible for more than 80% of all lung cancer worldwide. Harmful substances in smoke damage lung cells. Over time, the damaged cells may become cancerous. This is why smoking cigarettes, pipes, or cigars can cause lung cancer. Inhaling secondhand smoke can also cause lung cancer in non-smokers. The more a person is exposed to smoke, the greater the risk of lung cancer.
Other risk factors for lung cancer include radon (a radioactive gas), asbestos, arsenic, chromium, nickel and air pollution. People with family members who had lung cancer may be at slightly increased risk of the disease. People who have had lung cancer are at increased risk of developing a second lung tumor. Most people are older than 65 years of age when diagnosed with lung cancer.
Signs and Symptoms
Early lung cancer often does not cause symptoms. But as the cancer grows, common symptoms may include:
- A cough that gets worse or does not go away
- Breathing difficulties, such as shortness of breath
- Constant chest pain
- Coughing up blood
- A hoarse voice
- Frequent lung infections, such as pneumonia
- Feeling very tired all the time
- Weight loss with no known cause
Most often, these symptoms are not due to cancer. Other health problems can cause some of these symptoms. Anyone with such symptoms should see a doctor to be diagnosed and treated as early as possible.
Screening tests may help doctors find and treat cancer early. Several methods of detecting lung cancer have been studied as possible screening tests. The methods under study include tests of sputum (mucus brought up from the lungs by coughing), chest x-rays, or spiral (helical) CT scans.
You may want to talk with your doctor about your own risk factors and the possible benefits and harms of being screened for lung cancer. Like many other medical decisions, the decision to be screened is a personal one. Your decision may be easier after learning the pros and cons of screening.
Diagnosis & Assessment
If you have a symptom that suggests lung cancer, your doctor must find out whether it originates from cancer or other health conditions. You may be required to do some blood tests and diagnostic procedures:
- Physical Examination
- Chest X-ray
- Computed Tomography (CT) Scan
Your doctor may order one or more of the following tests to collect samples:
- Sputum cytology: Thick fluid (sputum) is coughed up from the lungs. The lab checks samples of sputum for cancer cells.
- Thoracentesis: The doctor uses a long needle to remove fluid (pleural fluid) from the chest. The lab checks the fluid for cancer cells.
- Bronchoscopy: The doctor inserts a thin, lighted tube (a bronchoscope) through the nose or mouth into the lung. The doctor may take a sample of cells with a needle, brush, or other tool. The doctor also may wash the area with water to collect cells in the water.
- Fine-needle aspiration: The doctor uses a thin needle to remove tissue or fluid from the lung or lymph node.
- Open biopsy: In cases where the tumor tissue is difficult to obtain, direct biopsy of the lung tumor or lymph nodes through an incision in the chest wall may be needed.
How is Lung Cancer assessed?
To plan the best treatment, your doctor needs to know the type of lung cancer and the extent (stage) of the disease. Staging is a careful attempt to find out whether the cancer has spread, and if so, to what parts of the body. Lung cancer spreads most often to the lymph nodes, brain, bones, liver, and adrenal glands.
Stages of Small Cell Lung Cancer
Doctors describe small cell lung cancer using two stages:
- Limited stage: Cancer is found only in one lung and its nearby tissues.
- Extensive stage: Cancer is found in tissues of the chest outside of the lung in which it began. Or cancer is found in distant organs.
Stages of Non–Small Cell Lung Cancer
- Occult stage: Lung cancer cells are found in sputum or in a sample of water collected during bronchoscopy, but a tumor cannot be seen in the lung.
- Stage 0: Cancer cells are found only in the innermost lining of the lung. The tumor has not grown through this lining. A Stage 0 tumor is also called carcinoma in situ. The tumor is not an invasive cancer.
- Stage I: Cancer cells are limited to the lung. Tissue around the lung remains normal.
- Stage II: Cancer has spread to lymph nodes, chest wall, diaphragm, lining of the lungs, or the outer lining that surrounds the heart.
- Stage III: Cancer has spread to the lymph nodes in the area of the chest between the heart and lungs. Blood vessels in this area may also be affected. Cancer may also have spread to the lower neck.
- Stage IV: Cancer has spread to the other lung or to other areas in the body and cannot be removed with surgery.
Treatment & Care
What treatment is offered?
Depending on the stage of the lung cancer, the aims of treatment may be for cure, control of disease for prolongation of survival or management of symptoms and prevention of complications to improve quality of life.
The following treatment modalities may be used singly or in combination.
Surgery for lung cancer involves the removal of tissues that contain the tumor and nearby lymph nodes.
Radiation therapy (also called radiotherapy) uses highenergy rays to kill cancer cells. It affects cells only in the treated area.
Chemotherapy uses anticancer drugs to shrink/kill cancer cells. The drugs enter the bloodstream and can affect cancer cells all over the body.
Targeted therapy uses drugs to block the growth and spread of cancer cells. The drugs enter the bloodstream and can affect cancer cells all over the body. Some people with non-small cell lung cancer that has spread receive targeted therapy.
What kind of support is available?
CanHOPE, is a non-profit cancer counselling & support service initiated by Parkway Cancer Centre.
As part of the holistic approach towards cancer treatment, CanHOPE works closely with the medical & allied health professionals, offering a wide range of resources & information about cancer in helping patients & their caregivers to make effective, informed decisions in their treatment journey.
Join us in our support programmes that are available on a monthly basis.
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