Lung Cancer - Small Cell: Diagnosis

Approved by the Cancer.Net Editorial Board, 09/2022

ON THIS PAGE: You will find a list of common tests, procedures, and scans that doctors use to find the cause of a medical problem. Use the menu to see other pages.

Doctors use many tests to find, or diagnose, cancer. They also do tests to learn if cancer has spread to another part of the body from where it started. If the cancer has spread, it is called metastasis. Doctors may also do tests to learn which treatments could work best.

For most types of cancer, a biopsy is the only sure way for the doctor to know if an area of the body has cancer. In a biopsy, the doctor takes a small sample of tissue for testing in a laboratory. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis.

How small cell lung cancer is diagnosed

There are many tests used for diagnosing this type of cancer. Not all tests described here will be used for every person. Your doctor may consider these factors when choosing a diagnostic test:

  • Size, location, and type of cancer suspected

  • Your signs and symptoms

  • Your age and general health

  • The results of earlier medical tests

In addition to a physical examination, the following tests may be used to diagnose and stage small cell lung cancer (SCLC):

  • Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope. A pathologist then analyzes the sample(s). A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease. If cancer cells are found, the pathologist will determine if it is SCLC or non-small cell lung cancer (NSCLC), based on what it looks like when seen through a microscope.

More procedures that doctors use to collect tissue for the diagnosis and staging of SCLC are listed below:

  • Bronchoscopy. In a bronchoscopy, the doctor passes a thin, flexible tube with a light on the end into the mouth or nose, down through the main windpipe, and into the breathing passages of the lungs. A surgeon or a pulmonologist may perform this procedure. A pulmonologist is a medical doctor who specializes in the diagnosis and treatment of lung disease. The tube lets the doctor see inside the lungs. Tiny tools inside the tube can take samples of fluid or tissue so the pathologist can examine them. Patients are given mild anesthesia during a bronchoscopy. Anesthesia is medication to block the awareness of pain.

  • Fine needle aspiration/core biopsy. After numbing the skin, a special type of radiologist, called an interventional radiologist, removes a sample of the lung tumor for testing. A fine needle aspiration uses a thin needle to remove a small sample of cells. A core biopsy is done with a wider needle. The type of needle used depends on how large of a sample is needed. Often, the radiologist uses a chest CT scan or special x-ray machine called a fluoroscope to guide the needle. In general, a core biopsy provides a larger amount of tissue than a fine needle aspiration. Doctors have learned that more tissue is needed to diagnose SCLC.

  • Thoracentesis. After numbing the skin on the chest, a needle is inserted through the chest wall and into the space between the lung and the wall of the chest where abnormal amounts of fluid can collect. The fluid is removed and checked for cancer cells by the pathologist.

  • Thoracoscopy. Through a small cut in the skin of the chest wall, a surgeon inserts a special instrument and a small video camera to assist in the examination of the inside of the chest. Patients need general anesthesia for this procedure, but recovery time may be shorter with a thoracoscopy because of the smaller incisions that are used. This procedure may be referred to as video-assisted thoracoscopic surgery or VATS.

  • Mediastinoscopy. A surgeon examines and takes a sample of the lymph nodes in the center of the chest underneath the breastbone by making a small incision at the top of the breastbone. This procedure also requires general anesthesia and is done in an operating room.

  • Thoracotomy. This procedure is performed in an operating room, and the patient receives general anesthesia. A surgeon then makes an incision in the chest, examines the lung directly, and takes tissue samples for testing. A thoracotomy is the procedure surgeons most often use to completely remove a lung tumor.

Imaging tests

In addition to biopsies and surgical procedures, imaging scans are very important in the care of people with SCLC. However, no test is perfect, and no scan can diagnose SCLC. Only a biopsy can do that. Imaging tests show pictures of the inside of the body. Chest x-ray and scan results must be combined with a person’s medical history, a physical examination, blood tests, and information from the biopsy to form a complete story about where the cancer began and whether or where it has spread.

  • CT scan. A CT scan produces images that allow doctors to see the size and location of a lung tumor and/or lung cancer metastases. This test takes pictures of the inside of the body using x-rays taken from different angles. A computer combines these pictures into a detailed, 3-dimensional image that shows any abnormalities or tumors. A CT scan can be used to measure the tumor’s size. Sometimes, a special dye called a contrast medium is given before the scan to provide better detail on the image. This dye can be injected into a patient’s vein or given as a pill or liquid to swallow.

  • Positron emission tomography (PET) scan. A PET scan is usually combined with a CT scan (see above), called a PET-CT scan. However, you may hear your doctor refer to this procedure just as a PET scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive sugar substance is injected into the patient’s body. This sugar substance is taken up by cells that use the most energy. Because cancer tends to use energy actively, it absorbs more of the radioactive substance. However, the amount of radiation in the substance is too low to be harmful. A scanner then detects this substance to produce images of the inside of the body.

  • Magnetic resonance imaging (MRI) scan. An MRI also produces images that allow doctors to see the location of a lung tumor and/or lung cancer metastases and measure the tumor’s size. An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. A special dye called a contrast medium is given before the scan to create a clearer picture. This dye can be injected into a patient’s vein or given as a pill or liquid to swallow. MRI scanning does not work well to take pictures of parts of the body that are moving, like your lungs, which move with each breath you take. For that reason, MRI is rarely used to look at the lungs. However, an MRI of the brain is recommended after the initial diagnosis of SCLC. This is because SCLC often spreads to the brain.

  • Bone scan. A bone scan uses a radioactive tracer to look at the inside of the bones. The amount of radiation in the tracer is too low to be harmful. The tracer is injected into a patient’s vein. It collects in areas of the bone and is detected by a special camera. Healthy bone appears lighter to the camera, and areas of injury, such as those caused by cancer, stand out on the image. PET scans (see above) have been replacing bone scans to find lung cancer that has spread to the bones.

After diagnostic tests are done, your doctor will review the results with you. If the diagnosis is cancer, these results also help the doctor describe the cancer. This is called staging.

Finding out where the cancer started

Lung cancer starts in the lungs. Many other types of cancer start elsewhere in the body and spread to the lungs when they metastasize. For example, breast cancer that has spread to the lungs is called metastatic breast cancer, not lung cancer. That's why it is important for doctors to know if the cancer started in the lungs or elsewhere.

To find where the cancer started, your doctor will take into account your symptoms and medical history, physical examination, how the tumor looks on x-rays and scans, and your risk factors for cancer. A pathologist can perform tests on the biopsy sample to help find out where the cancer began. Your doctor may recommend other tests to rule out specific types of cancer. If, after these considerations, the doctor is still not sure where the cancer started, you may be diagnosed with metastatic “cancer of unknown primary.” Most treatments for metastatic cancer of unknown primary that are first found in the chest are the same as those for metastatic SCLC.

Coping with a lung cancer diagnosis

For most patients, a diagnosis of SCLC is very stressful. Some patients with SCLC develop anxiety and, less commonly, depression. You and your family should not be afraid to express how you feel to doctors, nurses, and social workers. Your health care team is there to help and has special training and experience that can make things easier for you and your family.

In addition to emotional support and education, your doctor may prescribe anti-anxiety medication and occasionally, an antidepressant if it is needed. They may also refer you to a counselor, psychologist, social worker, or psychiatrist. There are also resources available in the community to help you and your family.

Some patients feel comfortable discussing their disease and experiences throughout treatment with their doctor, nurse, family, friends, or other patients through a support group. These patients may also join a support group or advocacy group in order to increase awareness about lung cancer and to help fellow patients who are living with this disease.

A SCLC diagnosis is serious. However, patients can be hopeful that their doctors can offer them effective treatment. They may also be able to take some comfort knowing that the advances being made in the diagnosis and treatment of lung cancer will provide more and more patients with a chance for cure.

Learn more about the counseling, finding a support group, and being a cancer advocate.

Stopping smoking

If you smoke, it is still beneficial to quit cigarette smoking even after SCLC is diagnosed. People who stop smoking have an easier time with all treatments, feel better, live longer, and have a lower risk of developing a second lung cancer or other health problems. Stopping smoking is never easy and even harder when facing a lung cancer diagnosis. People who smoke should seek help from family, friends, programs for quitting smoking, and health care professionals. None of the products available to quit smoking interfere with cancer treatment. Learn more about stopping tobacco use after a cancer diagnosis.

The next section in this guide is Stages. It explains the system doctors use to describe the extent of the disease. Use the menu to choose a different section to read in this guide.