The American Cancer Society describes the lungs as two sponge-like organs that are divided into sections called lobes. The left lung is smaller than the right lung to allow room for the heart. Tubes called bronchi link the lungs to the trachea, or wind pipe, where air is inhaled. Lung cancer occurs when a cell in the lung transforms into a cell that grows abnormally and damages the normal tissue around it. There are several types of lung cancer.
Small Cell Lung Cancer
Merck Manuals, an online medical library, reports that small cell lung cancer, also called oat cell carcinoma, makes up approximately 14 percent of all lung cancers. This type of lung cancer often begins in the bronchus near the center of the chest. Small cell lung cancer is an aggressive type of cancer, meaning that it grows and spreads to distant sites in the body quickly. The primary cause for this type of lung cancer is smoking cigarettes. The American Cancer Society notes that it is rare for someone who has never smoked to have this type of lung cancer. Small cell lung cancer often begins in the bronchus near the center of the chest.
Squamous Cell Carcinoma
The National Cancer Institute reports that about 87 percent of lung cancers are non-small cell lung cancer, of which there are several types. Non-small cell lung cancer tends to grow and spread more slowly than small cell lung cancer. One type of non-small cell lung cancer is squamous cell carcinoma. The American Cancer Society notes that this type of lung cancer accounts for 25 to 30 percent of all lung cancers. Similar to small cell lung cancer, squamous cell carcinoma is often caused by smoking cigarettes and also usually begins in a bronchus near the center of the chest.
Adenocarcinoma
Approximately 40 percent of all lung cancers are adenocarcinomas, according to the American Cancer Society. This type of lung cancer is often found in the cells of the outer portion of the lung. A diagnosis of adenocarcinoma often has a better prognosis than other forms of lung cancer.
Large-Cell Carcinoma
Large-cell carcinoma, also called undifferentiated carcinoma, is a third type of non-small cell lung cancer. It makes up 10 to 15 percent of all cancers of the lung. There is no particular part of the lung where this type of lung cancer usually begins. It also tends to grow and spread quickly. Treating cancers that have already metastasized (spread) make them considerably harder to treat than cancers that remain in the tissue of origin.
