- Risk Factors
- Signs & Symptoms
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.
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. (See 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.
Anything that increases your chance of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn't mean that you will not get cancer. People who think they may be at risk should discuss this with their doctor. Cigarette smoking is the most common cause of lung cancer. Risk factors for small cell lung cancer include:
- Smoking cigarettes, cigars, or pipes now or in the past.
- Being exposed to secondhand 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. Other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur:
- A cough that doesn't go away.
- Shortness of breath.
- Chest pain that doesn't go away.
- Coughing up blood.
- Swelling of the face and neck.
- Loss of appetite.
- Weight loss for no known reason.
- Unusual tiredness.
Tests and procedures that examine the lungs are used to detect (find), diagnose, and stage 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.
- 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.
- CT scan (CAT scan) of the brain, chest, and abdomen: A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
- PET scan (positron emission tomography scan): A procedure to find malignant tumor cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.
- Sputum cytology: A microscope is used to check for cancer cells in the sputum (mucus coughed up from the lungs).
- Bronchoscopy: A procedure to look inside the trachea and large airways in the lung for abnormal areas. A bronchoscope is inserted through the nose or mouth into the trachea and lungs. A bronchoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue samples, which are checked under a microscope for signs of cancer.
- Fine-needle aspiration (FNA) biopsy of the lung: The removal of tissue or fluid from the lung using a thin needle. A CT scan, ultrasound, or other imaging procedure is used to locate the abnormal tissue or fluid in the lung. A small incision may be made in the skin where the biopsy needle is inserted into the abnormal tissue or fluid. A sample is removed with the needle and sent to the laboratory. A pathologist then views the sample under a microscope to look for cancer cells. A chest x-ray is done after the procedure to make sure no air is leaking from the lung into the chest.
- Thoracoscopy: A surgical procedure to look at the organs inside the chest to check for abnormal areas. An incision (cut) is made between two ribs, and a thoracoscope is inserted into the chest. A thoracoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue or lymph node samples, which are checked under a microscope for signs of cancer. In some cases, this procedure is used to remove part of the esophagus or lung. If certain tissues, organs, or lymph nodes can't be reached, a thoracotomy may be done. In this procedure, a larger incision is made between the ribs and the chest is opened.
- Thoracentesis: The removal of fluid from the space between the lining of the chest and the lung, using a needle. A pathologist views the fluid under a microscope to look for cancer cells.
Certain factors affect prognosis (chance of recovery) and treatment options.
The prognosis (chance of recovery) and treatment options depend on the following:
- 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
After small cell lung cancer has been diagnosed, tests are done to find out if cancer cells have spread within the chest or to other parts of the body.
The process used to find out if cancer has spread within the chest or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment. Some of the tests used to diagnose small cell lung cancer are also used to stage the disease. (See the General Information section.) Other tests and procedures that may be used in the staging process include the following:
- 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.
- Bone marrow aspiration and biopsy: The removal of bone marrow, blood, and a small piece of bone by inserting a hollow needle into the hipbone or breastbone. A pathologist views the bone marrow, blood, and bone under a microscope to look for signs of cancer.
- MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI).
- Endoscopic ultrasound (EUS): A procedure in which an endoscope is inserted into the body. An endoscope is a thin, tube-like instrument with a light and a lens for viewing. A probe at the end of the endoscope is used to bounce high-energy sound waves (ultrasound) off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. This procedure is also called endosonography. EUS may be used to guide fine-needle aspiration (FNA) biopsy of the lung, lymph nodes, or other areas.
- Lymph node biopsy: The removal of all or part of a lymph node. A pathologist views the tissue under a microscope to look for cancer cells.
- Radionuclide bone scan: A procedure to check if there are rapidly dividing cells, such as cancer cells, in the bone. A very small amount of radioactive material is injected into a vein and travels through the bloodstream. The radioactive material collects in the bones and is detected by a scanner.
There are three ways that cancer spreads in the body.
The three ways that cancer spreads in the body are:
- Through tissue. Cancer invades the surrounding normal tissue.
- Through the lymph system. Cancer invades the lymph system and travels through the lymph vessels to other places in the body.
- Through the blood. Cancer invades the veins and capillaries and travels through the blood to other places in the body.
When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.
The following stages are used for small cell lung cancer:
Limited-Stage Small Cell Lung Cancer
In limited-stage, cancer is found in one lung, the tissues between the lungs, and nearby lymph nodes only.
Extensive-Stage Small Cell Lung Cancer
In extensive-stage, cancer has spread outside of the lung in which it began or to other parts of the body.
Recurrent Small Cell Lung Cancer
Recurrent small cell lung cancer is cancer that has recurred (come back) after it has been treated. The cancer may come back in the chest, central nervous system, or in other parts of the body.