Understanding Lung Cancer
- Understanding Lungs & Cancer
Your lungs are a pair of large organs in your chest. They are part of your respiratory system. Air enters your body through your nose or mouth. It passes through your windpipe (trachea) and through each bronchus, and goes into your lungs.
When you breathe in, your lungs expand with air. This is how your body gets oxygen.
When you breathe out, air goes out of your lungs. This is how your body gets rid of carbon dioxide.
Your right lung has three parts (lobes). Your left lung is smaller and has two lobes.
A thin tissue (the pleura) covers the lungs and lines the inside of the chest. Between the two layers of the pleura is a very small amount of fluid (pleural fluid). Normally, this fluid does not build up.
Cancer begins in cells, the building blocks that make up tissues. Tissues make up the organs of the body.
Normal, healthy cells grow and divide to form new cells as the body needs them. When normal cells grow old or become damaged, they die, and new cells take their place.
Sometimes, this orderly process goes wrong. New cells form when the body does not need them, and old or damaged cells do not die as they should. The build-up of extra cells often forms a mass of tissue called a growth or tumor.
Tumor cells can be benign (not cancer) or malignant (cancer). Benign tumor cells are usually not as harmful as malignant tumor cells:
- Benign lung tumors
- are rarely a threat to life
- usually do not need to be removed
- do not invade the tissues around them
- do not spread to other parts of the body
- Malignant lung tumors
- may be a threat to life
- may grow back after being removed
- can invade nearby tissues and organs
- can spread to other parts of the body
Cancer cells spread by breaking away from the original tumor. They enter blood vessels or lymph vessels, which branch into all the tissues of the body. The cancer cells attach to other organs and form new tumors that may damage those organs. The spread of cancer is called metastasis.
See “Stages of Lung Cancer” for information about lung cancer that has spread.
Content Created/Medically Reviewed by our Expert Doctors