Types of Lung Cancer - Overview

According to the American Cancer Society, lung cancer is the leading cause of cancer death for both men and women in the United States. Lung cancer mortality rates even exceed the deaths from breast, colon, and prostate cancers combined. This form of cancer mainly develops in the elderly, with fewer than 3 percent of cases being found in people under the age of 45.

According to a scientific study published in 2001, as much as 4 percent of all lung cancers diagnosed in the United States are caused by asbestos exposure. Asbestos has been associated with all major histological types of lung cancer, including small cell and non-small cell lung cancer. Those who smoke, or have ever smoked, and have been exposed to asbestos are at an even greater risk for developing lung cancer since the combination results a multiplicative synergism.

Classification of Lung Cancer

Lung cancer is classified into two major types: non-small cell and small cell. Non-small cell lung cancer (NSCLC) begins in the lungs' epithelial cells and is by far the most common type of lung cancer. Small cell lung cancer (SCLC) arises in the nerve cells or hormone-producing cells of the lung. The designation of non-small cell and small cell denotes the size and shape of the cancer cells when viewed under a microscope. This classification is very important, as each type of cancer is usually treated with different approaches. Though very uncommon, when a case of lung cancer bears characteristics of both types it is called mixed small cell/large cell carcinoma.

Aside from the two main classifications of lung cancer, other tumors can develop in the lungs as well. Carcinoid tumors, which usually develop in the gastrointestinal system, can form in the lungs. This cancer accounts for less than 5 percent of all lung tumors. Most cases of carcinoid cancer of the lungs are slow-growing tumors known as typical carcinoid tumors. Usually cured by surgery, typical carcinoid tumors bear a better prognosis than SCLC and NSCLC. Atypical carcinoid tumors can develop as well, but these are less common.
Other types of tumors that can develop in the lungs include hamartomas, lymphomas, sarcomas, and adenoid cystic carcinomas. These tumors are even rarer than carcinoid tumors.

Development of Lung Cancer

The majority of lung cancer is found in the bronchi, but it can also arise in the trachea, bronchioles, or alveoli. Specialists believe lung cancers develop over many years in areas of the lung where pre-cancerous changes take place on a cellular level. Areas experiencing pre-cancerous changes have yet to form a mass or tumor and do not cause any symptoms. Over a period of time, the pre-cancerous changes may develop into actual cancer.

In the beginning of the twentieth century, lung cancer was a very rare disease. But today lung cancer is the leading cause of cancer death and is the second most common cancer among both men and women. How did lung cancer go from a rare disease to one of the most prevalent and deadly in the United States? Quite simply, the answer is the introduction of manufactured cigarettes. Today, nearly 90 percent of lung cancer cases are caused by smoking.

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