What is lung cancer?
Lung cancer occurs when cells develop abnormally in one or both of the lungs and grow out of control to form a tumour. Tumours make it difficult for the lungs to work properly. There are two major types of lung cancer: non-small cell and small cell. The terms non-small cell and small cell refer to how the cells look when seen through a microscope. The terms refer to the kinds of cells that make up the tumour not the actual size of the tumour.
The Lungs
The lungs are organs where oxygen in the air is transferred into the bloodstream. The lungs consist of the air passages that carry the air that is breathed to the parts of the lung called the lung parenchyma. The lung parenchyma refers to the tissue where breathed air is allowed to exchange its oxygen with blood that is flowing through blood vessels in the lung tissue.
Non-Small Cell Lung Cancer
Over 75% of all people diagnosed with lung cancer have non-small cell lung cancer (NSCLC). Most people diagnosed with NSCLC are smokers or former smokers. There are four major types of non small cell lung cancer:
Squamous carcinoma
This type (also called Epidermoid carcinoma) generally begins in one of the larger breathing tubes (bronchus). It tends to spread less quickly than other forms of lung cancer. It currently occurs most frequently in men and older people of both sexes.
Adenocarcinoma
This type begins near the outside surface of the lung and can vary in both size and how fast it grows. It is the most common lung cancer among women.
Bronchoalveolar
This type is a variant of Adenocarcinoma. It causes changes on an x-ray that may be mistaken for pneumonia.
Large-cell carcinoma
This type may occur in any part of the lung. However, it usually starts in the smaller breathing tubes. Tumours are usually large at the time of diagnosis and occur with the same frequency in men and women.
Small Cell Lung Cancer
Small cell lung cancer (also called oat cell) is a more rapidly growing type of lung cancer than non-small cell lung cancer. Most people diagnosed with small cell lung cancer are smokers or former smokers. It usually starts in one of the larger breathing tubes and it tends to grow rapidly.
Other
Other types of cancer occur in a small number of patients, e.g. carcinoid.