Small-Cell Lung Cancer


What Is It?

Small-cell lung cancer has been called oat-cell cancer because the cells resemble oats when seen under a microscope. This cancer usually originates in the lung’s large central airways (the bronchi), and it accounts for about 20 percent of all lung cancers. In some cases, small-cell tumors also will include cells that have non-small-cell features. This condition is called a mixed tumor.

All types of lung cancer are associated strongly with smoking. About 90 percent of people who get small-cell lung cancer are either current or past smokers.

Because this type of cancer starts in special hormone-producing cells in the lung, it can cause unique sodium and water problems. For example, the tumor cells may secrete adrenocorticotropic hormone, causing Cushing’s disease. The tumors also may secrete antidiuretic hormone, leading to water retention and low sodium, which causes confusion. Small-cell cancer also can cause a specific type of weakness caused by antibodies produced as a result of the cancer. Small-cell lung cancer is among the fastest-growing cancers. In two-thirds of patients, the cancer already will have spread (metastasized) at the time of diagnosis. The cancer can spread easily because of the constant flow of fluids through the lungs. These fluids consist of blood and lymph (a protein-filled fluid from the lymphatic system). The fluids can carry cancer cells to lymph nodes, the heart, the other lung and to organs outside of the chest. Small-cell lung cancers spread more commonly to the brain, liver, adrenal glands and bone.


Although some cancers do not have any symptoms at first, others are diagnosed during an evaluation for any of the following:

  • A persistent cough
  • Coughing up of blood (hemoptysis)
  • Shortness of breath or wheezing
  • Unexplained weight loss or loss of appetite
  • Fatigue
  • Difficulty swallowing
  • Pain in the chest, shoulder or arm
  • Recurrent pneumonias in the same place
  • Bone pain
  • Hoarseness
  • Headaches, confusion or seizures
  • Swelling of the face, neck or upper extremities


Lung cancer often is discovered first on a chest X-ray, on which it appears as a gray or whitish area. Other imaging studies, such as computed tomography (CT) or magnetic resonance imaging (MRI), are used to further determine the size, shape and location of the tumor as well as to locate areas where the tumor has spread. This helps to find the best place to obtain a sample of the tumor to diagnose small-cell versus other types of lung cancer such as squamous cell or adenocarcinoma of the lung. The type of cancer affects what treatment you should get.

The cancer also can be diagnosed with a technique called sputum cytology, in which mucus from the lungs (sputum) is examined under a microscope to check for abnormal cells. Cancer cells also can be found in fluid between the lung and the chest wall (requiring a thoracentesis procedure using a needle to remove pleural fluid) or in lymph nodes next to the lung (requiring a mediastinoscopy surgical procedure).

Another diagnostic technique is needle aspiration, in which fluid or tissue is removed (aspirated) from lymph nodes or suspicious masses with the help of a CT scan done at the same time. Cells also can be removed during bronchoscopy. This is a procedure in which a fiber-optic viewing tube is directed into the lung through the mouth and the bronchial tubes. It allows the doctor to examine the tumor directly and also to remove cells for examination.

Your doctor will choose a therapy based on the location of the tumor and the degree to which it has spread. In addition to the above tests, you may need a bone scan, bone marrow biopsy, CT scan of the head and additional biopsies to determine the degree of tumor spread. Small-cell lung cancer has two stages: limited and extensive. Limited cancer is confined to one lung and nearby lymph nodes. Extensive cancer has spread to both sides of the chest or beyond the chest.

Expected Duration

As with any cancer, even if small-cell cancer disappears (goes into remission), there is a chance it can recur.


Quit smoking and avoid secondhand smoke. Tobacco smoke is the main risk factor for this cancer. Although studies are looking for screening tests to diagnose lung cancer earlier, no test has been proven effective.


Surgery rarely is done when small-cell lung cancer is diagnosed because the cancer grows quickly and usually has already spread to many lymph nodes or beyond the lung. Because this cancer grows so rapidly, chemotherapy is the cornerstone of therapy.

Treatment is tailored depending on stage or degree of cancer spread. The earlier stage allows for more intense and effective radiation therapy within a small area.

For the best chances of remission, radiation therapy typically is combined with chemotherapy, in alternating cycles. If a person has many other serious medical problems or cannot tolerate high-dose radiation or chemotherapy, he or she may be given altered doses to relieve specific symptoms such as bone pain. If tests show cancer remission at six to 12 weeks, some physicians will advise radiation to the brain to prevent the cancer from spreading there.

In patients with extensive-stage cancer, radiation usually isn’t used except to relieve specific symptoms, such as bone pain, that are caused by the spread of the tumor.

In rare cases, if the tumor has not spread to nearby lymph nodes, surgery is done to remove the tumor. This is more likely if the tumor is located at the borders of the lung instead of the more common central location. The chance for cure and prolonged survival is greater if surgery can be done, especially if chemotherapy is used as well.

When To Call A Professional

If you experience any symptoms of small-cell lung cancer, make an appointment to see your health-care provider as soon as possible.


Because small-cell lung cancer grows and spreads so rapidly, the prognosis is poor. The five-year survival rate is about 6 percent. The survival rate is higher when the disease is diagnosed and treated at the earlier limited stage.

Even when therapies are successful initially, there is a high risk of the cancer coming back. This reflects the fact that small-cell lung cancer rarely is restricted to just one area, but readily spreads to other parts of the body.

Johns Hopkins patient information

Last revised:

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