Small cell lung cancer

This page was reviewed under our medical and editorial policy by
Maurie Markman, MD, President, Medicine & Science at CTCA.

This page was updated on May 6, 2022.

Small cell lung cancer (SCLC) develops when nerve or hormone-producing cells of the lung start to grow uncontrollably and form a tumor. It takes its name from the typically small size and shape of these tumor cells, as seen under a microscope. It’s also known as “oat cell” cancer, because the cells may resemble oats.

An aggressive type of lung cancer, SCLC is responsible for 10 to 15 percent of lung cancer cases, according to the American Cancer Society (ACS).

What are the symptoms of SCLC?

Because SCLC grows quickly, most people with this type of cancer have symptoms at the time of diagnosis. Symptoms may worsen over weeks or days and include:

Other symptoms may develop if SCLC has spread (or metastasized) outside the lungs. These may depend on where the cancer has traveled.

If it spreads to:

  • Lymph nodes or skin—it may cause lumps or bumps
  • The brain—it may cause headaches, dizziness, seizures, double vision, numbness or tingling
  • The liver—it may cause jaundice (yellowing of the skin or eyes)
  • Bones—it may cause bone pain
  • What are the risk factors?

    The primary risk factor for SCLC is tobacco smoke. Secondhand smoke from cigarettes, pipes or cigars may also increase the chances of developing SCLC.

    Other risk factors may include:

    • Workplace exposure to toxins such as asbestos, arsenic, chromium, beryllium, nickel, soot or tar
    • Radiation exposure from imaging studies or radiation therapy
    • Radon gas exposure
    • Air pollution
    • Family history of lung cancer
    • HIV infection
    • Use of beta carotene supplements while being a smoker
    • Older age

    How is SCLC diagnosed?

    SCLC is usually diagnosed during a physical exam after noticeable symptoms.

    The next step typically involves imaging studies of the lung, using chest X-rays, a computed tomography (CT) scan or a positron emission tomography (PET) scan.

    Doctors may recommend a biopsy to see the cancer cells under a microscope and diagnose the type of cancer. Procedures used to remove the tissue may include a bronchoscopy, sputum cytology, needle biopsy, thoracoscopy or bone marrow biopsy.

    Although SCLC is usually diagnosed when symptoms develop, screenings may help with earlier detection. The American Society of Clinical Oncology (ASCO) recommends a yearly screening for people aged 55 to 74 who have smoked at least one pack of cigarettes a day for 30 years or more, even if they have quit in the past 15 years. Screenings may be done with a special type of CT scan that emits less radiation.

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    How is SCLC treated?

    After reviewing all diagnostic test results, doctors may proceed to staging the cancer. The stage of cancer, along with the patient’s age and general health, may help determine treatment options.

    The two-stage system is most commonly used for SCLC and includes:

    • Limited stage—The cancer is localized, meaning it’s confined to one lung. It may have spread to lymph nodes on the same side of the chest.
    • Extensive stage—The cancer is regional, having spread to lymph nodes on the other side of the chest, to the other lung, or to distant parts of the body.

    Treatment of SCLC may include:

    If the diagnosis is limited-stage SCLC, surgery may be used to remove the cancer, with a possible combination of radiation and chemotherapy. For extensive-stage SCLC, chemotherapy is typically the main treatment. Radiation therapy may be used to treat cancer that remains after chemotherapy, and immunotherapy may also be added to help the immune system fight the cancer.

    Patients also may be eligible for new treatments through clinical trials.

    What is the survival rate of SCLC?

    Doctors use what’s known as a five-year survival rate to predict cancer survival. This number is the percentage of patients who have survived for at least five years after diagnosis. For limited SCLC, that number is 27 percent, according to ASCO. The rate is 16 percent for regional cancer and 3 percent for cancer that has spread to a distant area. It’s important to know that five-year survival rates don’t account for new treatments that may become available.

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