Non-small cell lung cancer is a disease in which malignant (cancer) cells form in the tissues of the lung.

The lungs are a pair of cone-shaped breathing organs that are found within the chest. The lungs bring oxygen into the body and take out carbon dioxide, which is a waste product of the body’s cells. Each lung has sections called lobes. The left lung has 2 lobes. The right lung, which is slightly larger, has 3 lobes. A thin membrane called the pleura surrounds the lungs. Two tubes called bronchi lead from the trachea (windpipe) to the right and left lungs. The bronchi are sometimes also involved in lung cancer. Tiny air sacs called alveoli and small tubes called bronchioles make up the inside of the lungs.

There are several types of non-small cell lung cancer.

Each type of non-small cell lung cancer has different kinds of cancer cells. The cancer cells of each type grow and spread in different ways. The types of non-small cell lung cancer are named for the kinds of cells found in the cancer and how the cells look when viewed under a microscope:

Squamous cell carcinoma: Cancer that begins in squamous cells, which are thin, flat cells that look like fish scales. This is also called epidermoid carcinoma.

Adenocarcinoma: Cancer that begins in cells that have glandular (secretory) properties.

Large cell carcinoma: Cancer in which the cells are large and look abnormal when viewed under a microscope.

Adenosquamous carcinoma: Cancer that begins in cells that look flattened when viewed under a microscope. These cells also have glandular (secretory) properties.

Pleomorphic, sarcomatoid, or sarcomatous carcinoma: A group of cancers in which the cells look abnormal when viewed under a microscope.

Carcinoid tumor: A slow-growing neuroendocrine tumor (cancer that begins in cells that release a hormone in response to a signal from the nervous system).

Salivary gland carcinoma: Cancer that begins in salivary gland cells in large airways of the lung.

Unclassified carcinoma: Cancer that does not fit into a specific group.

• The stage of the cancer (whether it is in the lung only or has spread to other places in the body).
• The tumor size.
• The type of lung cancer.
• Whether there are symptoms.
• The patient’s general health.
• For most patients with non-small cell lung cancer, current treatments do not cure the cancer.

If lung cancer is found, participation in one of the many clinical trials being done to improve treatment should be considered. Clinical trials are taking place in most parts of the country for patients with all stages of non-small cell lung cancer.

National Cancer Institute