A. The vast majority - over 80% - of lung cancers are caused by smoking tobacco or by indirect exposure to tobacco smoke (passive smoking). The other main causes are breathing industrial chemicals such as asbestos, arsenic and polycyclic hydrocarbons or the natural radioactive gas, radon. 

Q. Who is at risk? 

A. Like most cancers, the risk of lung cancer increases with age. The longer you smoke, the greater your risk. Very few cases are diagnosed in people under 40 and the most common age of diagnosis is between 70 and 74. In the US 91,000 men and 79,000 women are diagnosed with lung cancer each year. In the UK the figures are 23,000 men and 15,000 women. 

Q. Does lung cancer run in families? 

A. There are very few, if any, inherited conditions that increase the risk of lung cancer in non-smokers. However, not all of the people who smoke get lung cancer and there may be an inherited component which influences whether or not smoking will cause lung cancer. 

A. This is still being investigated, but research to date has not found any link between diet and lung cancer. 

Q.. Are there different types of lung cancer? 

A. There are four main types of lung cancer: small cell lung cancer, squamous cell carcinoma, large cell carcinoma and adenocarcinoma. Tobacco smoking is strongly linked to the first three but only weakly linked to adenocarcinoma. However, this type of lung cancer has been linked to the use of low-tar cigarettes. 

Q. What are the symptoms of lung cancer? 

A. There are a variety of symptoms of lung cancer, including difficulty breathing, coughing up blood, chest pain, loss of appetite, weight loss and general fatigue. Some lung cancers do not cause any noticeable symptoms until they are quite advanced and have spread to other parts of the body. 

Q. How is lung cancer diagnosed? 

A. Lung cancers are sometimes first detected on routine chest X-rays. However, the main method of diagnosis is bronchoscopy, in which a thin, flexible tube 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. How is lung cancer treated? 

A. Drug treatment (chemotherapy) is the usual treatment for small cell lung cancers, because they usually spread too quickly for surgery to be useful. Radiotherapy is also often used. For the other types of lung cancer, surgery is first used to remove the main tumour, if it has not spread too far. If surgery is not possible, then radiotherapy is used instead. Depending on the type of tumour and how advanced it is, chemotherapy can be used in different ways: either to shrink the tumour before surgery or after surgery to kill off any remaining cancer cells. 

Q. How effective is the treatment? 

A. Lung cancer is one of the most dangerous cancers. The available treatments can prolong the patient's life, but complete cures are very rare. Four out of every five lung cancer patients die within one year of being diagnosed. Only one in twenty is alive five years after diagnosis. Many of these are people diagnosed with early squamous cell carcinomas, which can be treated successfully by surgical removal. 

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 special drugs. The hair loss may be partial or complete, but it is always temporary. The hair will grow back.