Lung cancer is the leading cause of cancer deaths in men and women in the United States as of 2007. Deaths from lung cancer surpass those from breast cancer, colon cancer and prostate cancer combined. While many cancers may metastasize (spread) to the lungs after beginning elsewhere in the body, lung cancer is specific to tumors originating from the respiratory tissue.
There are many different types of lung cancer, each with their own unique properties. They are named according to the cells in which they originate and the way the cells look under a microscope. For treatment purposes, lung cancers are categorized as either small cell lung cancer or non small cell lung cancer.
The three most common types of lung cancer are adenocarcinoma (and its subtypes), squamous cell carcinoma and small cell carcinoma.
Adenocarcinoma
Adenocarcinomas of the lung are a type of non small cell lung cancer that arises from glandular tissue and often appear in the outer areas of the lungs. They account for approximately 32 percent of all lung cancers. In 1987, adenocarcinoma surpassed squamous cell carcinoma as the most common form of lung cancer.
Squamous Cell Carcinoma
Squamous cell carcinoma is also called epidermoid carcinoma and originates in the squamous cells that line the lungs and other respiratory tissues. The cells are flat and thin with a scaly appearance. Squamous cell carcinoma of the lung accounts for approximately 29 percent of all lung cancers. However, squamous cells are present in other areas of body as well, such as the surface of the skin, where they can develop into cancer of those sites.
Small Cell Carcinoma
There are two types of small cell lung cancer: small cell carcinoma (also called oat cell carcinoma) and combined small cell carcinoma. Oat cell carcinoma is the most common of the two and the third most common of all lung cancers. Like all lung cancers, smoking is the number one risk factor for developing small cell lung cancer, and current smokers should quit to reduce their risks of developing lung cancer.
References
- Centers for Disease Control and Prevention: Lung Cancer Awareness
- "Harrison's Principles of Internal Medicine. 17th ed."; Anthony S. Fauci et al; 2008: p.551-2.
- National Cancer Institute: Cancer topics, NSCLC
- National Cancer Institute: Cancer Topics, SCLC
