How Is Small Cell Lung Cancer Diagnosed?

This content has been reviewed and approved by

Chandra P. Belani, MD
Deputy Director, Penn State Cancer Institute
Miriam Beckner Professor of Medicine
Penn State University School of Medicine

Detecting lung cancer early is critical to treatment and prolonging your life. However, the American Cancer Society does not recommend early screening devices, such as chest x-rays and examination of sputum (mucus from the lungs).

The ACS believes in most cases the tests do not detect cancer cells early enough to improve a person's chance for a cure. On the other hand, some doctors recommend smokers obtain annual screenings, particularly those over age 50.

As part of the diagnosis, the doctor must find out whether the cancer is a small cell or non-small cell type. The stage of the cancer (how far it has spread) must also be determined. This allows the doctor to decide on the best treatment.

Lung cancer may grow only in the lungs or spread (metastasize) to other sites in the body, including lymph nodes, bones, and the brain. Determining the presence and type of lung cancer requires examination of tissue from the lung. The procedure of removing a small piece of tissue for examination under a microscope is called a biopsy.

Your doctor will take a complete medical history to check for risk factors and symptoms. A physical examination will provide other information about signs of lung cancer and other health problems. In addition, other procedures that may be used to diagnose lung cancer include:

• Chest x-ray - to look for any mass or spot on the lungs.
• Computed tomography scan (also called a CT or CAT scan) - x-rays and computer technology are used to produce cross-sectional images (often called slices) of the body. A CT scan shows more detailed images of any part of the body than do x-rays. This includes the bones, muscles, fat, and organs. 
• Sputum cytology -  a study of phlegm (spit) to look for cancer cells under a microscope.  
  
• Needle biopsy (fine needle aspiration) - when the tumor mass is located peripherally in the chest, the doctor views your lungs on a CT scan and guides a needle into the tumor . A sample of the tissue is removed and evaluated in the pathology laboratory under a microscope. A lymph node biopsy may also be performed. Lymph nodes are located throughout your body. They act as filters and help to fight infection.
  
• Bronchoscopy -  the examination of the bronchi (the main airways of the lungs) using a flexible tube (bronchoscope). Bronchoscopy helps to evaluate and diagnose lung problems when the tumor mass is located centrally in the chest. It also assesses blockages, obtains samples of tissue and fluid, and helps remove foreign material.  
  
• Mediastinoscopy -  a process in which a small cut is made in the neck. The cut allows a tissue sample to be taken from the lymph nodes (mediastinal nodes) along the windpipe and the major bronchial tube areas. Tissue is then evaluated under a microscope.
  
• Positron emission tomography (PET) scan -  radioactive-tagged glucose (sugar) is injected into the bloodstream. Tissues that use the glucose more than normal tissues (such as tumors) are detected by a scanning machine. PET scans can be used to find small tumors or to check if treatment for a known tumor is working.
  
• X-rays and scans of the brain, liver, bones, and adrenal glands – used  to determine if the cancer has spread from where it started into other areas of the body.  
  
• Thoracentesis -  during a thoracentesis, a surgeon uses a needle to remove a sample of the fluid that surrounds the lungs. The fluid is  checked for the presence of cancer cells.
  
• Thoracotomy -  a thoracotomy is a major operation that involves opening the chest to diagnose lung cancer.
  
• Magnetic resonance imaging (MRI) -  during MRI, a powerful magnet linked to a computer makes detailed pictures of areas inside your body.
  
• Bone scan -  a bone scan is used to find out whether cancer has spread to the bones. Before a bone scan, a surgeon injects a small amount of radioactive substance into a vein. This substance travels through the bloodstream and collects in areas of abnormal bone growth. An instrument called a scanner measures the radioactivity levels in these areas and records them on x-ray film.