The lungs are a pair of cone-shaped breathing organs inside the chest. The lungs bring oxygen into the body when breathing in and send carbon dioxide out of the body when breathing out. Each lung has sections called lobes. Two tubes called bronchi lead from the trachea (windpipe) to the lungs.

The two main types of lung cancer are non-small cell lung cancer and small cell lung cancer. The types are based on the way the cells look under a microscope. Non-small cell lung cancer is much more common than small cell lung cancer.

Tobacco smoking is the most common cause of lung cancer. Lung cancer is the leading cause of death from cancer in the U.S. and the number of deaths from lung cancer in women is increasing.

There are three main types of lung cancer. Knowing which type you have is important because it affects your treatment options and your outlook (prognosis). If you aren’t sure which type of lung cancer you have, ask your doctor so you can get the right information.

Non-Small Cell Lung Cancer

This is the most common type of lung cancer. About 85% of lung cancers are non-small cell lung cancers. Squamous cell carcinoma, adenocarcinoma, and large cell carcinoma are all subtypes of non-small cell lung cancer.

Small Cell Lung Cancer

Small cell lung cancer is also called oat cell cancer. About 10%-15% of lung cancers are small cell lung cancers. This type of lung cancer tends to spread quickly.

Lung Carcinoid Tumor

Fewer than 5% of lung cancers are lung carcinoid tumors. They are also sometimes called lung neuroendocrine tumors. Most of these tumors grow slowly and rarely spread.