Overview
Lung cancer is the most common cause of cancer-related deaths and second most common cancer in both men and women in the United States. According to the National Cancer Institute, about 234,000 people in the U.S. are diagnosed with the disease each year. While most cases are linked to tobacco smoking, a growing number of diagnoses are among non-smokers, especially among women. Most lung cancers are diagnosed after the disease has spread. As a result, the five-year survival rate for lung cancers is just 19%.
Lung anatomy
When you breathe in, oxygen comes through your mouth and nose and then travels through the trachea, or windpipe. The trachea divides into two tubes called bronchi, which take the oxygen to the left and right lungs. Inside the lungs are smaller branches called bronchioles and alveoli, tiny air sacks where oxygen is transferred to the blood stream.
Each lung is divided into sections called lobes. The right lung has three lobes and the left lung has two lobes. The left lung is smaller than the right lung because the heart is also located in the left side of the chest. Each lobe can be further divided into bronchopulmonary segments.
The pleura is a thin membrane that covers the outside of each lung and lines the inside wall of the chest. The space between the lungs and the chest wall usually contains a very small amount of fluid that allows the lungs to move smoothly during breathing.
What are the risk factors for lung cancer?
A risk factor is anything that increases the chance that a person will develop a particular disease. The main risk factors for lung cancer are:
- A history of or current tobacco use
- Exposure to second-hand smoke
- Exposure to asbestos, arsenic, chromium or other chemicals
- Radiation exposure, including radiation therapy to the breast or chest and radon exposure.
- Living in an area with air pollution
- A family history of lung cancer
- Infection with the human immunodeficiency virus.