What Is Lung Cancer? Most cancers are named after the part of the body where the cancer first starts. Lung cancer begins in the lungs. The lungs are two sponge-like organs in the chest. The right lung has three sections, called lobes. The left lung has two lobes. It is smaller because the heart...

Lung cancer is not just one disease but rather a group of diseases. All forms of cancer cause cells in the body to change and grow out of control. Most types of cancer cells form a lump or mass called a tumor. Cells from the tumor can break away and travel to other parts of the body where they can c...