General Information About Lung Cancer
Key Points for This Section
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. The left lung has two lobes. The right lung, which is slightly larger, has three. 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 involved in lung cancer. Small tubes called bronchioles and tiny air sacs called alveoli make up the inside of the lungs.
See the following PDQ summaries for more information about lung cancer:
Anything that increases a person's chance of developing a disease is called a risk factor. The main cause of lung cancer is tobacco use, including smoking cigarettes, cigars, or pipes, now or in the past.
There are other risk factors for lung cancer, but even when taken together, their effect on lung cancer is very small compared to the effect of tobacco smoking. These include the following:
- Being exposed to second-hand smoke.
- Being exposed to asbestos, arsenic, chromium, nickel, or other substances in the workplace.
- Being exposed to radon, which can be found in the home as well as in the workplace.