Small cell lung cancer is a disease in which malignant (cancer) cells form in the tissues of the lung.
The lungs are a pair of cone-shaped breathing organs that are found within the chest. The lungs bring oxygen into the body when breathing in and take out carbon dioxide when breathing out. Each lung has sections called lobes. The left lung has two lobes. The right lung, which is slightly larger, has three. A thin membrane called the pleura surrounds the lungs. Two tubes called bronchi lead from the trachea (windpipe) to the right and left lungs. The bronchi are sometimes also involved in lung cancer. Small tubes called bronchioles and tiny air sacs called alveoli make up the inside of the lungs.
Anatomy of the respiratory system, showing the trachea and both lungs and their lobes and airways. Lymph nodes and the diaphragm are also shown. Oxygen is inhaled into the lungs and passes through the thin membranes of the alveoli and into the bloodstream (see inset).
There are two types of lung cancer: small cell lung cancer and non-small cell lung cancer. This summary provides information on small cell lung cancer. (Refer to the PDQ summary on Non-Small Cell Lung Cancer Treatment for more information.)
There are three types of small cell lung cancer.
These three types include many different types of cells. The cancer cells of each type grow and spread in different ways. The types of small cell lung cancer are named for the kinds of cells found in the cancer and how the cells look when viewed under a microscope:
- Small cell carcinoma (oat cell cancer).
- Mixed small cell/large cell carcinoma.
- Combined small cell carcinoma.
Smoking tobacco is the major risk factor for developing small cell lung cancer.
- Smoking cigarettes, cigars, or pipes now or in the past.
- Being exposed to second hand smoke.
- Being exposed to asbestos or radon.
Possible signs of small cell lung cancer include coughing, chest pain, and shortness of breath.
These and other symptoms may be caused by small cell lung cancer or by other conditions. A doctor should be consulted if any of the following problems occur:
Tests and procedures that examine the lungs are used to detect (find) and diagnose small cell lung cancer.
The following tests and procedures may be used:
- Chest x-ray: An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
X-ray of the chest. X-rays are used to take pictures of organs and bones of the chest. X-rays pass through the patient onto film.
- Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
- Sputum cytology: A microscope is used to check for cancer cells in the sputum (mucus coughed up from the lungs).
- Laboratory tests: Medical procedures that test samples of tissue, blood, urine, or other substances in the body. These tests help to diagnose disease, plan and check treatment, or monitor the disease over time.
- Bronchoscopy: A procedure to look inside the trachea and large airways in the lung for abnormal areas. A bronchoscope (a thin, lighted tube) is inserted through the nose or mouth into the trachea and lungs. Tissue samples may be taken for biopsy.
- Bronchoscopy. A bronchoscope is inserted through the mouth, trachea, and major bronchi into the lung, to look for abnormal areas. A bronchoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a cutting tool. Tissue samples may be taken to be checked under a microscope for signs of disease.
- Fine needle aspiration biopsy: The removal of part of a lump, suspicious tissue, or fluid, using a thin needle. A pathologist views the tissue or fluid under a microscope to look for cancer cells. This procedure is also called a needle biopsy.
- Thoracentesis: Removal of fluid from the pleural cavity (the space between the lungs and chest wall) through a needle inserted between the ribs.
Certain factors affect prognosis (chance of recovery) and treatment options.
- The stage of the cancer (whether it is in the chest cavity only or has spread to other places in the body).
- The patient’s gender and general health.
- The blood level of lactate dehydrogenase (LDH), a substance found in the blood that may indicate cancer when the level is higher than normal.
For most patients with small cell lung cancer, current treatments do not cure the cancer.
If lung cancer is found, participation in one of the many clinical trials being done to improve treatment should be considered. Clinical trials are taking place in most parts of the country for patients with all stages of small cell lung cancer. Information about ongoing clinical trials is available from NCI Web site.