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In Australia, lung cancer is one of the five most commonly diagnosed cancers, and causes more deaths than any other type of cancer. It has a 5-year survival rate of about 14%.
There are two types of lung cancer: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). NSCLC is the most common type of lung cancer. Compared with small cell lung cancer, it tends to grow and spread more slowly. NSCLC also differs in how it is treated.
There are a number of subtypes of NSCLC. These include squamous cell carcinoma (the most common subtype, a cancer that begins in squamous cells), adenocarcinoma (which develops in mucus-producing cells), and large cell carcinoma (this can begin in several types of large cells).
While the cause of NSCLC cannot be identified in every case, people who develop this cancer are usually smokers, or have been smokers in the past.
The main risk factors associated with developing lung cancer include:
• tobacco smoking (cigarettes, pipes or cigars)
• exposure to second-hand smoke (smoke breathed out by others)
• a family history of lung cancer
• being infected with HIV (human immunodeficiency virus)
• being treated with radiation therapy to the chest area
• being exposed to air pollution, radon (a radioactive gas), asbestos, or certain other chemicals.
In a small minority of cases, inherited DNA mutations appear to be linked to developing lung cancer. However, in most cases DNA mutations are acquired during a person’s lifetime, and occur as a result of exposure to environmental factors such as tobacco smoke.
Researchers continue to work on improving our understanding of the causes of lung cancer and how it might be prevented. Currently, the most important preventative measure is avoiding tobacco smoke.
Lung cancers diagnosed early are usually found by accident, such as when testing for other medical conditions. More often, the cancer is already advanced by the time symptoms appear.
When symptoms do develop, they may include:
• a persistent cough
• coughing up blood in the sputum
• shortness of breath
• chest pain
• loss of appetite
• unexplained weight loss
• difficulty swallowing
• swelling in the face and/or veins of the neck.
Aside from taking a medical history and conducting a physical examination, a number of tests may be done to diagnose lung cancer, such as:
• a chest x-ray
• biopsy (removing a sample of lung tissue for examination).
• laboratory testing of samples e.g. sputum, blood, urine
• imaging tests e.g. CT scan/CAT scan
• bronchoscopy (using a scope to look inside of the lungs)
• thoracoscopy (a surgical procedure to look at the organs inside the chest).
Other imaging tests, such as MR I scans, PET scans and bone scans may be done to check how far the cancer has spread.
The process used to determine how far cancer has spread at the time of diagnosis is called staging. Stages for NSCLC include the Occult /Hidden stage (when cancer cells have been found e.g. in the sputum, but cannot be seen by imaging or bronchoscopy), Stage 0 (when abnormal cells have been found in the lining of the airways), then Stages I to IV (which range from when the cancer is contained to one lung, through to when it has spread to the other lung and/or to lymph nodes and other areas of the body).
NSCLC can be treated with several different types of treatment, depending on the stage of the cancer at diagnosis and other factors. The main treatments include surgery, chemotherapy, radiotherapy, or a combination of these.
Surgery may be an option for people with early-stage lung cancer. Most often, this involves removing the lobe of the lung that contains the cancer (lobectomy). However, in some cases it may involve removal of an entire lung and nearby lymph nodes (pneumonectomy), or removal of a small area of the lung (wedge resection).
Radiation therapy may be used instead of, or as well as, surgery. If given before surgery to shrink the tumour, it is called neoadjuvant therapy. If given after surgery to try to kill any cancer cells remaining in the body, it is called adjuvant therapy. Radiation therapy can also be used to help relieve pain from cancer that has spread e.g. to the bones.
Chemotherapy (using anti-cancer drugs) can be used alone, or in combination with radiation therapy, or after surgery. The drugs are usually given directly into a vein (intravenously).
Other types of treatment for NSCLC include targeted therapies (such as monoclonal antibodies), laser therapy (using a laser beam to kill cancer cells), photodynamic therapy (using a drug and a laser light to kill cancer cells), cryosurgery (using an instrument to freeze and destroy abnormal tissue), and electrocautery (using a probe or needle heated by an electric current to destroy abnormal tissue).
Cancer researchers are continually working to improve the effectiveness of treatments for lung cancers. New drugs and new combinations of drugs are being investigated, as well as other therapies such as vaccines and anti-angiogenesis agents.
After treatment for lung cancer finishes, regular follow-up visits are required into the future. During these visits, tests such as blood tests, CT scans, or x-rays may be done, as well as physical examinations. Follow-up is done to check for any signs of the cancer returning, as well as to look for late effects of the treatments received.