Extensive-Stage Small Cell Lung Cancer

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Extensive stage small cell lung cancer (SCLC) is in the stage where it has spread to other parts of the body, such as the other lung or the brain. Without treatment, the average life expectancy for a person with an extensive-stage small cell lung cancer diagnosis is two to four months. With treatment, the expectancy rises to between six and 12 months, with a five-year survival rate of up to 4%.

The liver, adrenal glands, and bone are also common sites of metastasis. Unlike non-small cell lung cancer (NSCLC), which is divided into four main stages and several substages, extensive-stage is one of only two stages of SCLC (the other being limited stage).

Woman doctor discussing about problem in lung disease of Asian Elderly patient.
eggeeggjiew / Getty Images

SCLC is less common than NSCLC, accounting for about 10% to 15% of all lung cancers. It tends to be more aggressive, growing rapidly and spreading quickly. Though extensive-stage small cell lung cancer cannot be cured and has a poor prognosis, it may respond to chemotherapy and newer treatments.

Symptoms of Extensive-Stage SCLC

In the early, limited-stage of SCLC, you may have no symptoms at all. As the cancer progresses, you might begin to have a persistent cough or recurrent lung infections. These problems will continue to become more severe as the cancer grows and spreads, and you will develop increasingly debilitating symptoms.

Symptoms of extensive-stage small cell lung cancer can be categorized by those that affect the lungs, those caused by paraneoplastic syndromes (abnormal immune or hormone activity triggered by the tumor), and those related to metastasis.

Symptoms related to the lungs include:

Symptoms of paraneoplastic syndromes include:

  • Muscle weakness in the upper limbs, vision changes, and difficulty swallowing (Lambert-Eaton myasthenic syndrome)
  • Loss of coordination and difficulty speaking (paraneoplastic cerebellar degeneration)
  • Clubbing (rounding) of the fingernails
  • Weakness, fatigue, and a low sodium level in the blood (also known as the syndrome of inappropriate antidiuretic hormone secretion, or SIADH)

Symptoms related to metastasis include:


SCLC is initially caused by exposure to smoke or other toxins. In fact, approximately 95% of people diagnosed with SCLC are current or former smokers. Tobacco use is the biggest risk factor for small cell lung cancer.

Researchers believe that the carcinogens in tobacco smoke damage DNA in proto-oncogenes, which regulate cell growth, and tumor suppressor genes, which are involved in repairing or eliminating damaged cells. These mutated cells then grow uncontrollably and unchecked, quickly developing into malignant tumors.

Prolonged exposure to secondhand smoke also increases the risk of lung cancer, as does exposure to environmental agents, including asbestos and radon.

SCLC is often unnoticed in the early stages, usually progressing beyond the limited stage and transitioning to extensive stage before it's found.


Healthcare providers base their diagnosis of small cell lung cancer on several specialized tests, including:

  • Physical exam and health history: In addition to assessing your overall health, your healthcare provider will ask about your smoking history and possible job-related chemical exposure.
  • Laboratory tests: Samples of tissue, blood, urine, or other substances are examined and may be re-examined at a later time to check for changes.
  • Chest X-ray: Images of the organs and the bones in the chest will help identify tumors.
  • Computed tomography (CT) scan: Scans of the entire chest will be taken to check for abnormal tissue. Other locations, such as the brain and abdomen, may also be examined with scans to identify metastases.
  • Sputum cytology: A sample of mucus from the lungs is examined under a microscope to check for cancer cells.
  • Biopsy: Tissue and fluid samples are taken from the lung or areas of suspected metastases and examined for cancer cells.
  • Bronchoscopy: A scope with a camera is inserted through the nose or mouth, and placed down into the trachea and lungs to visually examine the lung tissue.
  • Thoracoscopy or mediastinoscopy: These surgical procedures involve the placement of camera scopes into the chest to view the area. A tissue sample may be taken for analysis as well.
  • Thoracentesis: Fluid is removed from the space between the lining of the chest and the lung to look for cancer cells.
  • Immunohistochemistry: Tissue samples are sent for lab analysis to check for certain antigens (markers) to help diagnose cancer and identify what type of cancer you have.

Roughly 60% to 70% of people with small cell lung cancer will have extensive disease at the time of diagnosis.

SCLC will be staged at the time of diagnosis. Healthcare providers will identify the cancer as extensive stage SCLC if it meets any of the following criteria:

  • Cancer has spread widely throughout the initial lung.
  • Tumors have spread to the other lung or to lymph nodes on the opposite side of the chest.
  • Cancer has spread to other parts of the body.

Sometimes the disease is also be considered extensive if it has spread to the fluid around the lung.


A combination of chemotherapy and immunotherapy drugs is the preferred regimen for the more advanced stage of small cell lung cancer.

  • Chemotherapy involves oral or intravenous administration of cytotoxic medications that kill cancer cells.
  • Immunotherapy drugs are medications that boost your immune system so you can effectively fight cancer. When these treatments are combined, they have been shown to prolong survival.

The currently recommended initial treatment regimen for extensive-stage small cell lung cancer is a platinum (carboplatin or cisplatin) combined with VePesid (etoposide) and immunotherapy (Tecentriq (atezolizumab) or durvalumab).

As it progresses, treatment options may switch from battling the cancer cells to easing symptoms. Radiation and chemotherapy may be used as palliative therapy at this point to help you manage pain or complications.


While treatments can relieve symptoms and extend life, extensive small cell lung cancer is not curable. Survival rates for small cell lung cancer have improved since the developments of new treatments, but still remain low.

Treatment of other fast-growing cancers, such as leukemia, has come a long way, and it is hoped that better treatments for small cell lung cancer will be found in the near future. For now, patients need to prepare for the likelihood that extensive small cell lung cancer will not go into remission, and if it does, it's likely to recur within two years.


Studies suggest that learning what you can about your lung cancer can improve your quality of life—and possibly even your outcome. Ask questions. Learn about clinical trials. Consider joining a support group.

Many hesitate to talk about end-of-life issues, but discussing these with your healthcare provider and your family—even if all of you are hoping for a cure—is associated with fewer feelings of loneliness and a better quality of life.

Never lose hope, even if you have chosen not to pursue further treatment. Hope for quality time with loved ones, with good control of your symptoms.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Lynne Eldridge, MD
 Lynne Eldrige, MD, is a lung cancer physician, patient advocate, and award-winning author of "Avoiding Cancer One Day at a Time."