Lung cancer is one of the most common types of cancer in the developed world. Here are some frequently asked questions about the symptoms, causes and treatment of the disease.
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Q. What is lung cancer?
A. Lung cancer is caused when cells in the lung start to multiply and grow out of control to form a mass or tumour.
Q. How common is lung cancer?
A. It is the most common cancer in the world, with about 1.6 million new cases diagnosed every year. Just over 40,000 of these are in the UK, 24,000 in Canada and 9,500 in Australia. In the USA an estimated 222,000 new cases are diagnosed each year.
Q. How dangerous is lung cancer?
A. Over 1.3 million people die every year from lung cancer, throughout the world. 35,000 of these are in the UK, 20,000 in Canada and 7,400 in Australia. In the USA lung cancer is estimated to kill 157,000 people each year.
Q. Are there different types of lung cancer?
A. There are two main types of lung cancer: small cell lung cancer and non-small cell lung cancer. Small cell is the rarer type, accounting for only one in 8 lung cancers. The more common non-small cell type can be further divided into squamous cell carcinoma, large cell carcinoma and adenocarcinoma.
There is a rare type of cancer that affects the lining of the lung or the abdomen and is called mesothelioma. Mesothelioma in the lungs is often caused by exposure to the insulating material asbestos and it is very different to lung cancer. Around 2,400 people are diagnosed with mesothelioma in the UK each year, although this includes mesothelioma in the abdomen.
Causes, Risks and Symptoms
Q. What causes lung cancer?
A. Nearly 90% of lung cancers are caused by smoking tobacco or by indirect exposure to tobacco smoke (passive smoking). Tobacco smoking is strongly linked to small cell and the first two types of non-small cell lung cancer, but only weakly linked to adenocarcinoma. However, this type of lung cancer has more recently been linked to the use of low-tar cigarettes. The other main causes of lung cancer are breathing industrial chemicals such as asbestos, arsenic and polycyclic hydrocarbons or the natural radioactive gas, radon, but these only account for a small fraction of cases.
Q. Who is at risk?
A. The longer a person smokes (or is exposed to second-hand smoke) the greater their risk. The more they smoke, the greater their risk. Very few cases are diagnosed in people under 40 and the most common age of diagnosis is between 70 and 74. In the past, more men than women got lung cancer, because more men were smokers. However, as smoking increased amongst women, the number of lung cancer cases has become nearly the same.
Q. Can lung cancer be prevented?
A. There is no known way of preventing lung cancer altogether, but non-smokers have 15-times less chance of getting it than smokers. Quitting smoking reduces the risk by between 2 and 10 times, depending on how long the person smoked and how long ago they stopped. The sooner they quit and the longer they stay off tobacco, the more their risk reduces.
Q. Does lung cancer run in families?
A. Recent research has confirmed that a higher risk of getting lung cancer does run in some families. The gene or genes responsible are currently being identified. Having a close relative (parent, child or sibling) with lung cancer doubles the risk that a person will also have it. This is regardless of whether they, or their relative, smoked.
Q. Does diet affect the risk of getting lung cancer?
A. This is still being investigated, but research to date has not found any reliable connection between diet and the risk of lung cancer.
Q. What are the symptoms of lung cancer?
A. There are a variety of symptoms of lung cancer, including difficulty breathing, persistent coughing, coughing up blood, chest pain, loss of appetite, weight loss, hoarseness and general fatigue. In a few cases, lung cancer causes ‘clubbing’ -enlargement of the ends of the fingers. Some lung cancers do not cause any noticeable symptoms until they are quite advanced and have spread to other parts of the body.
Diagnosis and Treatment
Q. How is lung cancer diagnosed?
A. If lung cancer is suspected, the first test is a chest X-ray. If this shows any abnormalities, further tests are usually done. These can include examining the sputum (the phlegm) for cancer cells and bronchoscopy. This uses a thin, flexible tube, which is inserted down the airways (under anaesthetic), allowing doctors to see the inside of the lungs and even take a biopsy (a sample small of the suspect tissue). A CT scan, liver ultrasound or bone scan may also be used to find out if the cancer has spread.
Q. Is early diagnosis important?
A. Like all cancers, treatments are much more effective if the cancer is at an early stage. For example, patients with non-small cell lung cancer who are treated with surgery, before it has spread, have about a 50% chance of being alive 5 years later. However, for patients who are diagnosed and treated after the cancer has spread, less than 10% survive for 5 years.
Q. How is lung cancer treated?
A. Small cell lung cancers spread quite early, so by the time they are diagnosed, surgery is no longer an option for the majority of cases. Drug treatment (chemotherapy) is the most common treatment for these cancers. In those cases that are diagnosed early enough, surgery can be used, usually followed by chemotherapy. Radiotherapy is used in the more advanced cases.
For non-small cell lung cancer, surgery is first used to remove the main tumour, if it has not spread too far. Chemotherapy can be given after the surgery to reduce the risk of the cancer recurring. In a few cases chemotherapy is given first, to shrink the tumour and make it easier to remove. If surgery is not possible, radiotherapy or chemotherapy are used, depending on how far the cancer has spread. Radiotherapy is most effective on tumours that have not spread too far, while chemotherapy is used for the more advanced cases.
Q. What are the side effects of treatment?
A. The drug treatments cause bruising, fatigue, hair loss, diarrhoea, nausea and vomiting. However, the nausea and vomiting can now be reduced or even eliminated by additional drugs. The hair loss may be partial or complete, but it is always temporary. The hair will grow back.
Q. How effective is the treatment?
A. Lung cancer is one of the most deadly cancers, because two thirds of patients are not diagnosed until the cancer is at an advanced stage when a cure is no longer possible. In most cases, the available treatments can prolong the patient's life, but not cure them. Long-term cures are very rare and restricted to patients diagnosed with early squamous cell carcinomas, which can be treated successfully by surgical removal.
Overall, two out of three lung cancer patients die within one year of being diagnosed. Only one in twelve is alive five years after diagnosis.
Sources of information
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