Small cell lung cancer is an aggressive cancer that grows and spreads faster than other types of lung cancer.

Small cell lung cancer (SCLC) is the least common type of lung cancer, comprising only 15% of all cases. This type of lung cancer tends to grow rapidly and spread early, making it more resistant to treatment. As a result, the disease has associations with more negative outcomes.

This article describes what SCLC is, including its symptoms, outlook, and treatment. We also outline the process for diagnosing SCLC and highlight some factors that can influence its spread.

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SCLC is a type of cancer that begins in the neuroendocrine cells within the lungs. These cells receive messages from neurotransmitters and respond by releasing hormones into the blood.

Medical experts sometimes refer to SCLC as oat cell cancer because its oval-shaped cells appear similar to oat grains under a microscope.

SCLC is an aggressive type of cancer. Compared with other solid tumors, SCLC has links to one of the highest concentrations of circulating cancer cells in the body.

Around 70% of people who receive a diagnosis of SCLC already have cancer in the lymph nodes or other parts of the body during diagnosis. And only one-third of individuals receive a diagnosis during the early stage of SCLC when the disease is more responsive to treatment.

Learn more about metastatic lung cancer.

The main risk factor for SCLC is tobacco use. Almost all people living with SCLC are current smokers or have a history of smoking.

Exposure to the following may also increase a person’s risk of SCLC:

  • pollution
  • radiation

Symptoms of SCLC can vary from person to person. There are rarely any noticeable symptoms early in the course of the disease. Signs and symptoms depend on the size and location of the tumor and typically appear 8–12 weeks before presentation.

Common symptoms include:

SCLC commonly spreads to the brain, liver, bone marrow, and adrenal glands. Additional symptoms depend on the affected areas and the extent of the disease. They may include:

People may also present with symptoms of paraneoplastic syndromes, a rare complication in response to cancer or atypical hormone production.

Among solid tumors, SCLC is the most common cause of paraneoplastic syndromes. These rare disorders arise due to an atypical immune system response to cancer. They can also develop due to the atypical production of hormones.

In SCLC, the most common paraneoplastic syndromes and their associated symptoms include:

  • Syndrome of inappropriate antidiuresis: Symptoms include weakness and an altered sense of taste.
  • Ectopic Cushing syndrome: Symptoms may include:
    • swelling, or edema
    • weakness in both upper or lower limbs
    • hypokalemic alkalosis, which occurs due to insufficient potassium levels
  • Lambert-Eaton Myasthenic syndrome: Symptoms typically include weakness in the arms and legs.

Compared with other cancers, lung cancer has a high risk of spreading or “metastasizing.” However, certain factors may slow down the progression of the disease.

Smoking has links to 85% of all lung cancer cases, with the strongest link occurring in SCLC. Carcinogens in tobacco smoke can damage DNA in both typical cells and cancer cells, which can accelerate the growth and progression of cancer.

Medical experts classify SCLC into two stages: limited stage disease, which has a more favorable prognosis, and extensive stage disease, which has a less favorable prognosis.

According to a 2021 review, nearly 70% of people have extensive stage disease at the time of diagnosis. At this stage, the cancer is not curable. Most people die within 24 months, and fewer than 2% live 5 years beyond their diagnosis.

Among individuals with limited stage disease, 80% live for 2 years with radiation therapy and chemotherapy treatments. However, fewer than 15% of people reach 5 years of survival.

Factors that may affect survival include:

  • losing beyond 10% of baseline body weight
  • inability to perform strenuous activities
  • low sodium levels
  • recurrence of the cancer

Treatment for SCLC depends on the stage of the disease. Other factors to consider include the person’s age and overall health status.

Below are some possible treatment options for SCLC.

Radiation therapy

Radiation therapy uses a machine to deliver high-energy X-rays directly to the tumor. Doctors may use radiation therapy to treat SCLC or for palliative therapy to relieve symptoms and improve quality of life.

Doctors may also administer low dose radiation therapy to the brain to help reduce the risk of SCLC spreading to this organ.


Chemotherapy involves using anticancer drugs to help stop cancers from growing and replicating.

People with limited stage SCLC may receive a combination of chemotherapy and radiation therapy called “chemoradiation.”

People with extensive stage SCLC may receive chemotherapy with or without immunotherapy. The latter are drugs that help the immune system to fight cancer.

Types of chemotherapy

Doctors typically give people a combination of chemotherapy drugs. Common combinations include:

  • cisplatin and etoposide
  • cisplatin and irinotecan
  • carboplatin and etoposide
  • carboplatin and irinotecan


The method of administration for chemotherapy drugs depends on the cancer type and stage. Options may include:

  • administering the drugs orally
  • injecting the drugs into a vein or muscle
  • infusing the drugs into the bloodstream over several hours
  • administering the drugs directly into the cerebrospinal fluid or organs


Immunotherapy stimulates a person’s immune system to recognize and kill cancer cells.

Immune checkpoint inhibitor therapy is a type of immunotherapy that doctors may use to manage advanced SCLC. Doctors give these drugs through intravenous infusion. Examples include atezolizumab (Tecentriq) and durvalumab (Imfinzi).


Surgery for SCLC may be an option if the cancer is limited to one lung and nearby lymph nodes. The procedure will involve removing part or all of the affected lung.

Surgical options include:

  • Pneumonectomy: Removal of an entire lung.
  • Lobectomy: Removal of a section or lobe of a lung.
  • Segmentectomy: Removal of a section of a lobe.
  • Sleeve resection: Removal of a lobe and parts of the airway.

Clinical trials

A person may ask their doctor about participating in ongoing clinical trials to improve treatments for SCLC. People can also visit the National Cancer Institute’s website for further information.

Most people with SCLC experience signs and symptoms of the disease during the later stages. Sometimes, a doctor may detect abnormalities during lung cancer screening for individuals at risk of lung cancer.

Diagnosis will involve the following:

  • assessing symptoms
  • assessing a person’s medical and family history
  • a physical examination of the lungs

If the doctor is concerned about the possibility of lung cancer, they will order one of the following imaging tests to check for signs of the disease:

While a person’s symptoms and imaging test results may strongly indicate SCLC, a doctor will need to investigate a lung cell sample to make a definitive diagnosis.

Some methods for collecting lung cell samples include:

  • Sputum sample: Analyzing mucus that a person coughs up from the lungs.
  • Thoracentesis: Draining fluid that has collected around the lungs.
  • Needle biopsy: Using a needle to remove cells from a suspicious-looking area within the lungs.
  • Bronchoscopy: Using a bronchoscope to look for abnormalities in the airways. A bronchoscope is a thin tube with a light and camera attached. The doctor inserts the bronchoscope through the nose or mouth.
  • Thoracoscopy: Using a thoracoscope to look for abnormalities in the chest cavity, in the areas outside of the lungs. The surgeon inserts the thoracoscope through a small incision between the ribs.
  • Mediastinoscopy: A surgical procedure that looks for abnormalities in the mediastinum, the space between the two lungs. This area contains various structures and tissues, including several lymph nodes.

Learn more about lung biopsy.

SCLC is an aggressive form of lung cancer that grows and spreads rapidly. There are two main stages of SCLC: limited stage and extensive stage, with most people having the latter at the time of diagnosis. In extensive stage SCLC, the disease has already spread to other organs or tissues beyond the lungs.

There is no cure for SCLC. Depending on its stage, treatment can help delay the progression of the disease, alleviate symptoms, and improve quality of life. Treatment options may include surgery, radiation therapy, chemotherapy, immunotherapy, or a combination. People who smoke should also aim to quit smoking.

Because of the negative outcomes associated with SCLC, medical experts are focusing on early screening and prevention. Early screening can detect SCLC when the disease is more responsive to treatment.