Lung cancer is cancer that usually starts in the lining of the bronchi (the main airways of the lungs), but can also begin in other areas of the respiratory system, including the trachea, bronchioles, or alveoli. It is the leading cause of cancer death in both men and women. In 2015, 221,200 new cases of lung cancer are expected, according to the American Cancer Society.
Lung cancers are believed to develop over a period of many years.
Nearly all lung cancers are carcinomas, cancers that begin in the lining or covering tissues of an organ. The tumor cells of each type of lung cancer grow and spread differently, and each type requires different treatment. About 85 percent to 90 percent of lung cancers belong to the group called non-small cell lung cancer.
Lung cancers are generally divided into two types:
- Non-small cell lung cancer is much more common than small cell lung cancer. There are several types of non-small cell lung cancer, named for the type of cells found in the tumor:
- Squamous cell carcinoma, also called epidermoid carcinoma, is the most common type of lung cancer in men. It often begins in the bronchi and usually does not spread as quickly as other types of lung cancer.
- Adenocarcinoma usually begins along the outer edges of the lungs and under the lining of the bronchi. This type of non-small cell lung cancer begins in cells that have secretory (glandular) characteristics. It is the most common type of lung cancer in people who have never smoked.
- Large cell carcinomas are a group of cancers with large, abnormal-looking cells. These tumors usually begin along the outer edges of the lungs.
- Adenosquamous carcinoma begins in flattened cells when viewed under a microscope. These cells also have secretory characteristics.
- Undifferentiated carcinoma involves abnormal-looking cancer cells that tend to multiply quickly.
- Small cell lung cancer, sometimes called oat cell cancer because the cancer cells may look like oats when viewed under a microscope, grows rapidly and quickly spreads to other organs. There are two stages of small cell lung cancer:
- limited - cancer is generally found only in one lung. There may also be cancer in nearby lymph nodes on the same side of the chest.
- extensive - cancer has spread beyond the primary tumor in the lung into other parts of the body. It is important to find out what kind of lung cancer a person has. The different types of carcinomas, involving different regions of the lung, may cause different symptoms and are treated differently.
The following are the most common symptoms for lung cancer. However, each individual may experience symptoms differently.
Lung cancer usually does not cause symptoms when it first develops, but they often become present after the tumor begins growing. A cough is the most common symptom of lung cancer. Other symptoms include:
- constant chest pain
- shortness of breath
- recurring lung infections, such as pneumonia or bronchitis
- bloody or rust colored sputum
- swelling of the neck and face caused by a tumor that presses on large blood vessels near the lung
- pain and weakness in the shoulder, arm, or hand caused by a tumor that presses on certain nerves near the lung
- fever for unknown reason
Like other cancers, lung cancer can cause:
- loss of appetite
- loss of weight
- pain in other parts of the body not affected by the cancer
- bone fractures
Other symptoms can be caused by substances made by lung cancer cells - referred to as a paraneoplastic syndrome. Certain lung cancer cells produce a substance that causes a sharp drop in the level of sodium in the blood, which can cause many symptoms, including confusion and sometimes even coma.
None of these symptoms is a sure sign of lung cancer. The symptoms of lung cancer may resemble another medical condition or problem. Always consult your physician for a diagnosis.