How Is Extensive Small-Cell Lung Cancer Diagnosed?

Medically Reviewed by Laura J. Martin, MD on January 29, 2023

If you have extensive small-cell lung cancer but didn’t notice any symptoms at first, you’re far from alone. When this disease begins, you may not feel any warning signs. Your doctor may discover it by accident. But it progresses quickly. By the time you have symptoms, it may have spread far beyond the lung in which it started. This is when it reaches the extensive stage.


You may confuse some early symptoms with colds and other ills. You may have noticed:

  • A cough that just won’t get better
  • Coughing up blood
  • Pain in your chest when you cough
  • Shortness of breath
  • Wheezing
  • Hoarseness
  • Tiredness
  • Weight loss that you can’t explain
  • Chest pain
  • Trouble swallowing

But two-thirds of people with small-cell lung cancer aren’t diagnosed until their condition reaches the extensive stage.

Some symptoms may affect more than the lungs. Where you’ll notice them depends on what parts of the body the cancer has reached. Among them:

  • Yellowish skin or eyes (from cancer in your liver)
  • Bone pain  
  • Headaches or double vision (from cancer in your brain)
  • Tingling in your arms and legs (from cancer in your brain)


You’ll likely need at least several tests before your doctor can decide whether you have small-cell lung cancer. If they find that you do have it, they’ll look to see how far it has spread. This will determine if you’re in the limited or extensive stage.

With limited small cell, the condition hasn’t advanced much. You can’t find it outside the lung, the tissues between the lungs, or the nearby lymph nodes.  

Before they run more complex tests, your doctor usually will examine you and check your lung function. They’ll ask about your symptoms and how long these have bothered you.


To diagnose small-cell lung cancer, your doctor will get a bit of tissue or cells to study under a microscope.  They can take this sample, or biopsy, in several ways:

  • Sputum cytology. Your doctor may ask you to cough up some phlegm. They’ll look at the mucus under a microscope to see if they can find cancer cells. This gives some helpful information, but not enough to diagnose small cell lung cancer.
  • Bronchoscopy. You may have a procedure to see inside your lungs. First, you’ll get  mild anesthesia. Then the doctor will thread a lighted tube through your mouth or nose into the airways that lead to your lungs. They can see into your lungs and take a bit of fluid or tissue to study further.
  • Fine needle aspiration/core biopsy. A doctor also can take a tissue sample by inserting a needle into your chest. With the help of an imaging scan, they can guide the needle through the chest wall into your lung.
  • Thoracentesis. In this procedure, the doctor may use a needle to pull fluid from the area between a lung and the chest wall. They’ll look at that fluid for any cancer cells.
  • Thoracotomy. Your doctor may suggest you undergo surgery under anesthesia, so they can remove a tissue sample after making a cut in the chest wall.  

Getting a Fuller Picture

Once they’ve identified your cancer, your doctor can order imaging scans and other tests to learn more about how far it has spread:

CT scan. Your doctor may order this test to get a better picture of the size of the lung cancer, as well as where else it is in the body.

PET-CT. Your CT may be paired up with something called a PET (positron emission tomography) scan. For the PET, you’ll get an injection of a radioactive sugar substance. The radioactive sugar acts as a tracer in your body to show which ones may be cancerous.

MRI (magnetic resonance imaging). This type of scan uses magnetic fields instead of radiation to take a picture. But it doesn’t work well with moving organs, such as the lungs. So your doctor may order it only to look at other parts of your body.

Bone scan. Your doctor may order this test if they suspect that the cancer has spread to your bones. To search for signs of spread, they’ll inject a radioactive tracing substance into one of your blood vessels. A special camera then searches for areas where your bone may have cancer damage.  

Before you start treatment, you may opt to have another lung cancer specialist review your biopsy and other tests. Small-cell lung cancer can sometimes be misdiagnosed as the more common form this disease, which is non-small-cell lung cancer. Since the treatment can be different for small cell, it’s important to make sure to have your diagnosis confirmed before you start the next stage of your medical care.

Show Sources

SOURCES: “Lung Cancer - Small Cell: Introduction,” “Lung Cancer - Small Cell: Diagnosis.”

National Cancer Institute: “Dictionary of Cancer Terms,” “Small Cell Lung Cancer Treatment (PDQ®)–Health Professional Version.”

National Organization for Rare Disorders: “Small Cell Lung Cancer.”

UpToDate: “Patient education: Small cell lung cancer treatment (Beyond the Basics).”

Dana-Farber Cancer Institute: “Small Cell Lung Cancer.”

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