Classification of Lung Cancer

There are important classification of Lung Cancer which started in the lungs and others lung cancer that has spread to the lung from another part of the body. Basically, The lung cancer has divided into two criteria according to the level spread of lung cancer it self :

Primary lung cancer (cancer that has started in the lungs)

Secondary lung cancer (cancer that has spread to the lungs)

1. Primary Lung Cancer

Lung cancer which include in this criteria are divided into two main types; Small cell lung cancer (SCLC) and Non-small cell lung cancer (NSCLC). These two types of cancers grow and spread in different ways, so a distinction between these two types is important. This classification is based upon the microscopic appearance of the tumor cells themselves.

a. Small cell lung cancer (SCLC)
SCLC accounts for about 20% of all lung cancers, these cancers are sometimes called oat cell carcinomas. Although the cells are small, they multiply quickly and form large tumors that can spread throughout the body. Small cell lung cancer (SCLC) are usually responds better to the chemotherapy and radiation therapy.

SCLC are strongly related to cigarette smoking, with only 1% of these tumors occurring in nonsmokers. The occurrence of lung cancer in non-smokers, who account for fewer than 10% of cases, appears to be due to a combination of genetic factors, radon gas, asbestos, and air pollution, including second-hand smoke.

b. Non-small cell lung cancer (NSCLC)
Non-small cell lung cancer accounts for about 80% of lung cancers. The NSCLC are diveded into three subtypes such as Squamous cell carcinoma (also called epidermoid carcinoma), Adenocarcinoma and Large cell carcinoma.

- Squamous cell carcinomas were formerly more common than adenocarcinomas, its increase most frequently in the central chest area in the bronchi which known as epidermoid carcinomas. These is the most common type of lung cancer in men.

- This cancer is found in the glands of the lungs that produce mucus. While adenocarcinomas are associated with smoking like other lung cancers, this type is especially observed as well in nonsmokers who develop lung cancer. These is the most common type of lung cancer in women.

- These is type of lung cancer that forms near the surface, or outer edges, of the lungs. This type of lung cancer tends to grow quite quickly, sometimes referred to as undifferentiated carcinomas, are the least common type of NSCLC.


2. Secondary Lung Cancer
Secondary lung cancer is cancers that has spread from another part of the body. There are quite a few different cancers that can spread to the lungs, including breast cancer and bowel cancer.

Cancers from anywhere in the body may spread to the lungs either through the bloodstream, lymphatic system, or by directly from nearby organs. The metastatic tumors (cancers) are most often multiple, scattered throughout the lung, and concentrated in the peripheral rather than central areas of the organ.