Cancer - Lung

The Lungs The chest cavity ('thorax') is the area enclosed by your ribs, from below your neck and shoulders. Its floor is the diaphragm, a wide, thin dome of muscle a little above your waist. Below the diaphragm is the abdomen. Most of the chest cavity is filled with two large, spongy lungs. The lungs are roughly cone-shaped, and are made up of sections or lobes - the left lung has two and the right lung has three. Between the lungs is the mediastinum, an area that contains the heart and large blood vessels, the trachea (windpipe), the oesophagus (the tube that carries food from mouth to stomach), and many glands called lymph nodes. When we breathe in, air goes through the nose or mouth, into the throat, and down the windpipe into the chest. The windpipe branches into two bronchi, one going to each lung. Inside the lungs, the bronchi branch many times, like a tree, to form smaller bronchi and then thousands of tiny tubes (bronchioles). Each bronchiole ends up at tiny, bubble-like air sacs. It is these air sacs (alveoli) that make the lungs spongy. | Blood flows between the thin walls of adjacent air sacs. This allows oxygen to move from the air into the blood, and carbon dioxide a waste product from the body - to move from blood to air, to be breathed out. A double layer of thin membrane called the pleura surrounds the lungs. It is about the thickness of plastic cling wrap. The inner layer is attached to the lungs and the outer layer lines the chest wall and diaphragm. Between the two layers is the pleural cavity. This cavity is virtually empty ? the two layers of pleura slide against each other, and they are moist and smooth so that your lungs can move smoothly against the chest wall as you breathe. Lung Cancer Lung cancer is cancer of some of the cells in part of your lung, usually beginning in the lining of the airway. A cancer that arises in cells lining an organ is called a carcinoma. There are different types of lung cancer. Lung cancers are classified according to the type of cell affected. There are two main types: small cell carcinomas and non-small cell carcinomas. Small cell carcinomas Small cell carcinomas, also called oat cell carcinomas because of the cell shape, account for around 15 per cent of lung cancers. This type of lung cancer is strongly associated with cigarette smoking. Unfortunately, it spread early and causes few initial symptoms, with the result that more often than not it has already metastasised at the time of diagnosis. Non-small cell carcinomas Non-small cell carcinomas include squamous cell carcinoma, adenocarcinoma, large cell carcinoma, bronchiolo-alveolar cell carcinoma and mesothelioma. These carcinomas affect the cells that line the main bronchi. As these tumours enlarge they can spread into the chest wall and local lymph nodes. Squamous cell carcinoma has a lower rate of metastasis (spread to other parts of the body) than other types of lung cancer and is generally discovered earlier, resulting in the best prognosis following treatment. Mesothelioma is not, strictly speaking, a lung cancer. It is a rare cancer of the pleural membranes on the surface of the lungs and is strongly related to asbestos exposure.