Types of Lung Cancer
Non-Small Cell Lung Cancer (NSCLC)
Most lung cancers are classified as non-small cell lung cancer (NSCLC). About half of these are squamous cell carcinomas (SCC). SCC, sometimes called epidermoid carcinoma, is more prevalent in men and arises in the lining of the large air passageways, or bronchi. Another common type of NSCLC is adenocarcinoma, which occurs at the outer edges of the lung. A small percentage of NSCLC are large-cell carcinomas, which usually develop in the smaller bronchi. Non-small cell lung cancer that begins at the top of the lung sometimes spreads to the nerves and blood vessels leading to the arm.
- Squamous cell or epidermoid carcinomas usually occur in the bronchi in the center of the lungs, but about a third of them arise on the periphery. This type of NSCLC is more likely to cause ulcers in the bronchi and bleeding than the other forms. Typically, the cancer cells double every 180 days. Although it often invades nearby tissue, squamous cell carcinoma is less likely to metastasize as soon as other types.
- Most adenocarcinomas begin in the middle of the lungs, but about 25 percent develop along the lung periphery. These tumors are small, and the cells double about every 180 days also. They are likely to metastasize early. The form known as bronchoalveolar adenocarcinoma develops in the alveoli and may spread through the airways to other parts of the lung.
- Large cell carcinomas are bulky tumors that usually develop on the organ's periphery; however, they can arise anywhere within the lung. The cells double about every 100 days and can invade the mediastinum during the course of the disease.
Small Cell Lung Cancer (SCLC)
About one in four malignancies involving the lungs are diagnosed as small cell lung cancer (SCLC). There are several types of SCLC or oat cell cancer, including a mix of small cell and other cell types. These cancers grow rapidly—doubling in cell number about every 30 days—and spread quickly to lymph nodes and other organs than the non-small cell type.