It's one of those tricky cancers that shows few symptoms in the early stages, meaning that by the time it is diagnosed, it may be quite advanced.
Primary lung cancer is classed by the type of cells where the cancer begins. Non-small-cell lung cancer is the most common type - it tends to account for about 80% of all cases. The other type is less common - it is called small-cell lung cancer and spreads faster than the other type of lung cancer.
According to the NHS, the main symptoms of lung cancer are:
:: a cough that doesn’t go away after two or three weeks
:: a long-standing cough that gets worse
:: persistent chest infections
:: coughing up blood
:: an ache or pain when breathing or coughing
:: persistent breathlessness
:: persistent tiredness or lack of energy
:: loss of appetite or unexplained weight loss.
Less common symptoms include:
:: changes in the appearance of your fingers, such as becoming more curved or their ends becoming larger
:: a high temperature (fever) of 38C (100.4F) or above
:: difficulty swallowing or pain when swallowing
:: a hoarse voice
:: swelling of your face or neck
:: persistent chest or shoulder pain.
It's worth noting that in some cases these may be symptoms of much less serious ailments. If in doubt, speak to your GP.
Like most cancers, there are some undetermined reasons, but the most common is smoking.
According to Cancer Research UK: "Smoking causes nearly 9 out of 10 cases (86%). A further 3% of cases of lung cancer are caused by exposure to second hand smoke in non smokers (passive smoking)."
Other causes include exposure to radon gas (a radioactive substance), air pollution and family history. As for diet and lifestyle, more work needs to be done before conclusive findings are drawn.
However - a healthy lifestyle is important because if you do have lung cancer, your treatment and recovery will depend not only on the stage of cancer but how good your general health is.
The NHS says: "If the condition is diagnosed early and the cancerous cells are confined to a small area, surgery to remove the affected area of lung is usually recommended. If surgery is unsuitable due to your general health, radiotherapy to destroy the cancerous cells may be recommended instead.
"If the cancer has spread too far for surgery or radiotherapy to be effective, chemotherapy is usually used."