Cancer Types – Lung Cancer

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Lung Cancer: Overview

Approved by the Cancer.Net Editorial Board, 06/2014

About the lungs

When a person inhales, the lungs absorb oxygen from the air and bring the oxygen into the bloodstream for delivery to the rest of the body. As the body’s cells use oxygen, they release carbon dioxide. The bloodstream carries carbon dioxide back to the lungs, and the carbon dioxide leaves the body when a person exhales. The lungs contain many different types of cells. Most cells in the lung are epithelial cells. Epithelial cells line the airways and make mucus, which lubricates and protects the lung. The lung also contains nerve cells, hormone-producing cells, blood cells, and structural or supporting cells.

About lung cancer

Lung cancer begins when cells in the lung change and grow uncontrollably, forming a mass called a tumor, a lesion, or a nodule. A lung tumor can begin anywhere in the lung. A tumor can be cancerous or benign. Once a cancerous lung tumor grows, it may or may not shed cancer cells. These cells can be carried away in blood or float away in the fluid, called lymph, that surrounds lung tissue. Lymph flows through tubes called lymphatic vessels that drain into collecting stations called lymph nodes, the tiny, bean-shaped organs that help fight infection. Lymph nodes are located in the lungs, the center of the chest, and elsewhere in the body. The natural flow of lymph out of the lungs is toward the center of the chest, which explains why lung cancer often spreads there first. When a cancer cell moves into a lymph node or to a distant part of the body through the bloodstream, it is called metastasis.

Types of lung cancer

There are two major types of lung cancer: non-small cell and small cell.

Non-small cell lung cancer (NSCLC). NSCLC comes from epithelial cells and is the most common type. NSCLC may also be described based on the type of epithelial cell where the cancer starts. Adenocarcinoma starts in cells that produce mucus. Squamous or epidermoid carcinoma begins in the cells that line the airways. Large cell carcinoma begins in cells other than the two types described above.

Small cell lung cancer. Small cell lung cancer begins in the nerve cells or hormone-producing cells of the lung. The term “small cell” refers to the size and shape of the cancer cells as seen under a microscope.

It is important for doctors to distinguish NSCLC from small cell lung cancer because the two types of cancer are usually treated in different ways. The type of lung cancer, such as NSCLC or small cell, and stage of the disease (discussed later in the Stages section) determine what type of treatment is needed.

Read more about lung cancer here.

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