Primary lung cancer

Alternative names:

bronchogenic cancer; cancer of the lung; lung cancer

Definition:

A malignant tumor that arises from lung tissue.

Causes, incidence, and risk factors:

Most lung cancers (83%) are associated with, and probably caused by, cigarette smoking. The more cigarettes smoked per day and the earlier the age at which smoking started, the greater the risk of lung cancer. Second-hand smoke has also been shown to increase the risk. Government surveys show that as many as 3,000 people each year develop lung cancer from second-hand smoke. High levels of pollution, radiation, and asbestos exposure may also increase the risk. Cooks and chemists also have an increased risk.

Lung cancer begins by cellular changes in the bronchial epithelial cells and can invade adjacent tissues before symptoms are noticed.

There are many types of lung cancer, but most can be categorized into two basic types, small cell and nonsmall cell. In general, the small cell type has usually spread by the time of diagnosis and is treated by chemotherapy and/or radiation therapy. The nonsmall type may not have spread at the time of diagnosis, and surgical resection of this type may be possible. Metastatic lung cancer (the spread of cancer) can occur to almost any area of the body with common sites being the brain, bone, bone marrow, and liver. Treatment is based on determining the cellular type of the cancer, and by staging, which determines the size of the primary tumor and the extent of spreading to lymph nodes or sites of metastasis. Lung cancer is the leading cause of death in both men and women. The peak incidence occurs between 55 and 65 years old. The incidence is 1 out of 1,000 people.