Non-small-cell lung cancer

Non-small-cell lung cancer overview

Cancers are diseases in which normal cells transform so that they grow and multiply without normal controls. In many types of cancer, this results in the growth of one or more large masses, or tumours, of these transformed cells. This can happen in almost any part of the body. When it happens in the lungs, the disease is called lung cancer.
 
Lung cancer is one of the most common types of cancer; this is because the lungs are exposed to the external environment more than most other organs are. In many cases, cancer-causing substances (carcinogens) in the air are inhaled and cause cell damage that later becomes cancer. The most common cause of lung cancer, without a doubt, is smoking.
 
Two main types of lung cancer exist: small cell lung cancer and non-small-cell lung cancer. Non-small-cell lung cancer is a catchall term for all lung cancers that are not small-cell type. They are grouped together because the treatment is the same for all non-small-cell types. Together, non-small-cell lung cancers, or NSCLCs, make up about 80% of all lung cancers. Each type is named after the types of cells that were transformed to become cancer. The following are the 3 most common types of NSCLC in the United Kingdom. 

• Squamous cell carcinoma - 35%
• Adenocarcinoma/bronchoalveolar - 27%
• Large-cell carcinoma - 10% 

Like all cancers, lung cancer is most easily and successfully treated if it is caught early. An early-stage cancer is less likely to have grown to a large size or to have spread to other parts of the body (metastasised). Large or metastasised cancers are much more difficult to treat.

Non-small-cell lung cancer causes

Tobacco smoking

• Tobacco smoking is the cause of lung cancer in as many as 90% of cases.
• A person who smokes is 13.3 times more likely to develop lung cancer than a person who has never smoked. The risk also varies with the number of cigarettes smoked per day; people who smoke more than 20 cigarettes a day have a much greater risk of developing lung cancer than do those who smoke fewer than 20 cigarettes a day.
• Once a person stops smoking, the risk of lung cancer will gradually decrease, but never quite returns to the same level as that of a person who has never smoked.
• Not all people who smoke develop lung cancer, and not all people with lung cancer smoke. Clearly, other factors, including genetic predisposition and exposure to other harmful agents, also play a role.

Passive smoking (secondhand smoke)

• As many as 15% of lung cancer cases involving nonsmokers may be caused by secondhand smoke.
• The British Medical Association has recognised passive smoking as a potential cause of cancer.

Asbestos

• Asbestos exposure has been linked to lung cancer, particularly a type of lung cancer called mesothelioma, and other lung diseases.
• The silicate type of asbestos fibre is an important carcinogen.
• Asbestos exposure increases the risk of lung cancer by as much as 5 times.
• People who both smoke and have been exposed to asbestos are at an especially high risk of developing lung cancer.