Types of Lung Cancer

There are two main types of lung cancer: non-small cell lung cancer, which accounts for about 85 percent of all lung cancers, and small cell lung cancer, which makes up about 15 percent.

Non-small Cell Lung Cancer

Non-small cell lung cancer is classified into three main subtypes.

  • Adenocarcinoma begins in the glands that line the airways and is often found in an outer area of the lung. About 40 percent of lung cancers are adenocarcinomas. This is the most common type of lung cancer in non-smokers.
  • Squamous cell or epidermoid carcinoma is usually located in the center of the lung next to one of the main air passages (bronchi). Squamous cell carcinomas account for about 25 to 30 percent of all lung cancers.
  • Large cell carcinoma can occur in any part of the lung but is most commonly found near the outer region of the lung. Large cell carcinomas tend to grow and spread faster than the other two types. This type accounts for about 10 to 15 percent of lung cancers.

Small Cell Lung Cancer

Small cell lung cancer usually starts in the bronchi. Although the cancer cells are small, they grow very quickly and create large tumors. These tumors often spread rapidly to other parts of the body, including the brain, liver, and bone. Most small cell lung cancers spread outside the lung before they are discovered. Small cell lung cancer occurs almost exclusively in heavy smokers.


Mesothelioma is another, less common, type of cancer related to the lungs. This cancer affects the pleura, the membrane that covers the lungs and lines the chest cavity. It is often linked to asbestos exposure.