Most cancers are named after the part of the body where the cancer first starts. 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 takes up more room on that side of the body. The lungs bring air in and out of the body, taking in oxygen and getting rid of carbon dioxide gas, a waste product. .
The lining around the lungs, called the pleura, helps to protect the lungs and allows them to move during breathing. The windpipe (trachea) brings air down into the lungs. It divides into tubes called bronchi, which divide into smaller branches called bronchioles. At the end of these small branches are tiny air sacs known as alveoli. .
Most lung cancers start in the lining of the bronchi but they can also begin in other areas such as the trachea, bronchioles, or alveoli. Lung cancer often takes many years to develop. Once the lung cancer occurs, cancer cells can break away and spread to other parts of the body. Lung cancer is a life-threatening disease because it often spreads in this way before it is found. .
Imaging tests: these tests use x-rays, magnetic fields, sound waves or radioactive substances to create pictures of the inside of the body. Some of the imaging tests used to find lung cancer and to see where in the body it may have spread include x-rays, CT scan (computed tomography), MRI (magnetic resonance imaging), PET (positron emission tomography) scans, and bone scans. .
Sputum cytology: a sample of phlegm (spit) is looked at under a microscope to see if cancer cells are present. .
Needle biopsy: a needle is placed into the tumor to remove a piece of tissue. The tissue is looked at in the lab to see if cancer cells are present. .
Bronchoscopy: a lighted, flexible tube is passed through the mouth into the bronchi. This test can help find tumors or it can be used to take samples of tissue or fluids to see if cancer cells are present.