How do your lungs work?
To understand lung cancer it is helpful to understand your lungs. Your lungs put oxygen into the blood, which the heart then pumps throughout the body. When blood returns to the lungs, they remove carbon dioxide, a gas your body does not need, from the blood, put oxygen back into the blood, and the process starts over again.
Each lung is surrounded by a thin lubricating layer, called the pleura. The pleura is surrounded by the chest wall. The dome-shaped muscle under the lungs is called the diaphragm. As the diaphragm contracts and relaxes with each breath, it causes air to move in and out of the lungs.
What is cancer?
Your body's tissues, organs and all the parts of your body are made up of millions of individual cells. These cells have a life cycle of growth, duplication and death. New duplicated cells replace older dying or damaged cells. This is a fine-tuned mechanism throughout your life. This mechanism can break down. New cells can be made when they aren't needed. This out of control duplication can result in a tumor. A tumor may be benign or cancerous.