What Is It?

Lung cancer (or carcinoma) is one of the most common cancers diagnosed in both men and women. There are two general categories of lung cancer, small cell lung cancer (SCLC) or non small lung cancer (NSCLC). There are several reasons for making the distinction between NSCLC and small cell lung cancer. The cancers appear differently when examined under the microscope. The early symptoms tend to be different. Treatment approach is different.

There are several varieties of non small lung cancer. These include large cell lung cancer, squamous cell lung cancer and adenocarcinoma of the lung.

While most lung cancers are directly related to cigarette smoking or other tobacco exposure, other chemicals and exposures to agents such as asbestos, radon, chromium, nickel and arsenic may be associated with the development of lung cancer.

Squamous cell carcinoma of the lung accounts for about 30% of cases of non-small cell lung cancer. Most squamous cell carcinoma starts in the central areas of the lungs. These tumors may cause symptoms of coughing up blood at an earlier stage than tumors located on the edges of the lungs, such as adenocarcinoma. The proportion of lung cancers labeled squamous has been steadily decreasing, possibly because people began inhaling smoke more deeply into more peripheral areas of the lung after the advent of filtered cigarettes.

Squamous cell carcinoma often spreads (metastasizes) to other parts of the body because of the constant flow of fluids (blood and lymph) through the lungs. The fluids can carry cancer cells to nearby areas, such as the chest wall, neck, esophagus or heart. Unless the cancer is diagnosed and treated early, it frequently spreads throughout the body. Outside the chest, this lung cancer commonly spreads to the bones, brain, liver and adrenal glands. In addition, many lung cancers may secrete unusual types of chemicals that circulate in the blood stream. Squamous cell lung cancer may secrete a substance that may abnormalities of the calcium levels of the bloodstream. This can lead to abnormalities of kidney function as well. When cancers secrete chemicals that cause other portions of the body to react, this phenomenon is called a "paraneoplastic phenomenon."