Your lungs are 2 sponge-like organs in your chest. Your right lung has 3 sections, called lobes. Your left lung has 2 lobes. The left lung is smaller because the heart takes up more room on that side of the body.
When you breathe in, the air enters through your mouth or nose and goes into your lungs through the trachea (windpipe). The trachea divides into tubes called bronchi, which enter the lungs and divide into smaller bronchi. These divide into smaller branches called bronchioles. At the end of the bronchioles are tiny air sacs known as alveoli.
The alveoli absorb oxygen into your blood from the inhaled air and remove carbon dioxide from the blood when you exhale. Taking in oxygen and getting rid of carbon dioxide are your lungs main functions.
Lung cancers typically start in the cells lining the bronchi and parts of the lungs such as the bronchioles or alveoli. The illustration below shows details of the lungs and surrounding areas. A thin lining layer called the pleura surrounds the lungs. The pleura protects your lungs and helps them slide back and forth against the chest wall as they expand and contract during breathing.
Below the lungs, a thin, dome-shaped muscle called the diaphragm separates the chest from the abdomen. When you breathe, the diaphragm moves up and down, forcing air in and out of the lungs.
What is Lung Cancer?
Lung cancer is a type of cancer that starts in the lungs. Cancer starts when cells in the body begin to grow out of control. For more information, please visit the American Cancer Society.
There are 2 main types of lung cancer and they are treated very differently.
Non-small cell lung cancer (NSCLC) – About 80-85 percent of lung cancers are NSCLC. The main subtypes of NSCLC are adenocarcinoma, squamous cell carcinoma, and large cell carcinoma. These subtypes, which start from different types of lung cells are grouped together as NSCLC because their treatment and prognoses are often similar.
Adenocarcinoma starts in the cells that would normally secrete substances such as mucus. This type of lung cancer occurs mainly in current or former smokers, but it is also the most common type of lung cancer seen in non-smokers. It is more common in women than in men, and it is more likely to occur in younger people than other types of lung cancer.
Squamous cell carcinoma: Squamous cell carcinoma starts in squamous cells, which are flat cells that line the inside of the airways of the lungs. They are often linked to a history of smoking and tend to e found in the central part of the lungs, near a main airway (bronchus).
Large cell (undifferentiated) carcinoma can appear in any part of the lung. It tends to grow and spread quickly, which can make it harder to treat. A subtype of large cell carcinoma, known as large cell neuroendocrine carcinoma, is a fast growing cancer that is very similar to small cell lung cancer.
Small cell lung cancer (SCLC) make up only 10-15 percent of all lung cancers. Sometimes it is called oat cell cancer. This type of lung cancer tends to grow and spread faster than NSCLC. About 70% of people with SCLC will have cancer that has already spread at the time they are diagnosed. Since this cancer grows quickly, it tends to respond well to chemotherapy and radiation therapy. Unfortunately, for most people, the cancer will return at some point.
Cancers that start in other organs can sometimes metastasize (spread) to the lungs, but they are not lung cancers. For example, cancer that starts in the breast and spreads to the lungs is still considered breast cancer, not lung cancer.