Lung cancer forms in tissues of the lung, usually in the cells lining air passages. The two main types are small cell lung cancer and non-small cell lung cancer. These types are diagnosed based on how the cells look under a microscope.
Cancer begins in cells, the building blocks that make up tissues. Tissues make up the organs of the body. Normal cells grow and divide to form new cells as the body needs them. When normal cells grow old or get damaged, they die, and new cells take their place. Sometimes, this process goes wrong. New cells form when the body doesn't need them, and old or damaged cells don't die as they should. The buildup of extra cells often forms a mass of tissue called a growth or tumor.
Doctors cannot always explain why one person develops lung cancer and another does not. However, we do know that a person with certain risk factors may be more likely than others to develop lung cancer. A risk factor is something that may increase the chance of developing a disease. Studies have found the following risk factors for lung cancer:
Tobacco smoke: Tobacco smoke causes most cases of lung cancer. It's by far the most important risk factor for lung cancer. Harmful substances in smoke damage lung cells. That's why smoking cigarettes, pipes, or cigars can cause lung cancer and why secondhand smoke can cause lung cancer in nonsmokers. The more a person is exposed to smoke, the greater the risk of lung cancer.
Radon: Radon is a radioactive gas that you cannot see, smell, or taste. It forms in soil and rocks. People who work in mines may be exposed to radon. In some parts of the country, radon is found in houses. Radon damages lung cells, and people exposed to radon are at increased risk of lung cancer. The risk of lung cancer from radon is even higher for smokers.
Asbestos and other substances: People who have certain jobs (such as those who work in the construction and chemical industries) have an increased risk of lung cancer. Exposure to asbestos, arsenic, chromium, nickel, soot, tar, and other substances can cause lung cancer. The risk is highest for those with years of exposure. The risk of lung cancer from these substances is even higher for smokers.
Air pollution: Air pollution may slightly increase the risk of lung cancer. The risk from air pollution is higher for smokers.
Family history of lung cancer: People with a father, mother, brother, or sister who had lung cancer may be at slightly increased risk of the disease, even if they don't smoke.
Personal history of lung cancer: People who have had lung cancer are at increased risk of developing a second lung tumor.
Age over 65: Most people are older than 65 years when diagnosed with lung cancer.
Researchers have studied other possible risk factors. For example, having certain lung diseases (such as tuberculosis or bronchitis) for many years may increase the risk of lung cancer. It's not yet clear whether having certain lung diseases is a risk factor for lung cancer.
People who think they may be at risk for developing lung cancer should talk to their doctor. The doctor may be able to suggest ways to reduce their risk and can plan an appropriate schedule for checkups. For people who have been treated for lung cancer, it's important to have checkups after treatment. The lung tumor may come back after treatment, or another lung tumor may develop.
Your doctor may refer you to a specialist who has experience treating lung cancer, or you may ask for a referral. You may have a team of specialists. Specialists who treat lung cancer include thoracic (chest) surgeons, thoracic surgical oncologists, medical oncologists, and radiation oncologists. Your health care team may also include a pulmonologist (a lung specialist), a respiratory therapist, an oncology nurse, and a registered dietitian.
Lung cancer is hard to control with current treatments. For that reason, many doctors encourage patients with this disease to consider taking part in a clinical trial. Clinical trials are an important option for people with all stages of lung cancer.
The choice of treatment depends mainly on the type of lung cancer and its stage. People with lung cancer may have surgery, chemotherapy, radiation therapy, targeted therapy, or a combination of treatments.
People with limited stage small cell lung cancer usually have radiation therapy and chemotherapy. For a very small lung tumor, a person may have surgery and chemotherapy. Most people with extensive stage small cell lung cancer are treated with chemotherapy only.
People with non-small cell lung cancer may have surgery, chemotherapy, radiation therapy, or a combination of treatments. The treatment choices are different for each stage. Some people with advanced cancer receive targeted therapy.