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Health A-Z

Medical Content Created by the Faculty of the
Harvard Medical School

Diagnosis

Your doctor may suspect lung cancer based on

  • your symptoms

  • your smoking history

  • whether you live with a smoker

  • your exposure to asbestos and other cancer-causing agents.

To look for evidence of cancer, your doctor will examine you, paying special attention to your lungs and chest. He or she will order imaging tests to check your lungs for masses. In most cases, a chest x-ray will be done first. If the x-ray shows anything suspicious, a CT scan will be done. As the scanner moves around you, it takes many pictures. A computer then combines the images. This creates a more detailed image of the lungs, allowing doctors to confirm the size and location of a mass or tumor.

You may also have a magnetic resonance imaging (MRI) scan or a positron emission tomography (PET) scan. MRI scans provide detailed pictures of the body's organs, but they use radio waves and magnets to create the images, not x-rays. PET scans look at the function of tissue rather than anatomy. Lung cancer tends to show intense metabolic activity on a PET scan. Some medical centers offer combined PET-CT scanning.

If cancer is suspected based on these images, more tests will be done to make the diagnosis, determine the type of cancer, and see if it has spread. These tests may include the following:

  • Sputum sample. Coughed up mucus is checked for cancer cells.

  • Biopsy. A sample of abnormal lung tissue is removed and examined under a microscope in a laboratory. If the tissue contains cancer cells, the type of cancer can be determined by the way the cells look under the microscope. The tissue is often obtained during a bronchoscopy. However, surgery may be necessary to expose the suspicious area.

  • Bronchoscopy. During this procedure, a tube-like instrument is passed down the throat and into the lungs. A camera on the end of the tube allows doctors to look for cancer. Doctors can remove a small piece of tissue for a biopsy.

  • Mediastinoscopy. In this procedure, a tube-like instrument is used to biopsy lymph nodes or masses between the lungs. (This area is called the mediastinum.) A biopsy obtained this way can diagnose the type of lung cancer and determine whether the cancer has spread to lymph nodes.

  • Fine-needle aspiration. With a CT scan, a suspicious area can be identified. A tiny needle is then inserted into that part of the lung or pleura. The needle removes a bit of tissue for examination in a laboratory. The type of cancer can then be diagnosed.

  • Thoracentesis. If there is fluid build-up in the chest, it can be drained with a sterile needle. The fluid is then checked for cancer cells.

  • Video-assisted thoracoscopic surgery (VATS). In this procedure, a surgeon inserts a flexible tube with a video camera on the end into the chest through an incision. He or she can then look for cancer in the space between the lungs and the chest wall and on the edge of the lung. Abnormal lung tissue can also be removed for a biopsy.

  • Bone scans and CT scans. These imaging tests can detect lung cancer that has spread to the bones, brain, or other parts of the body.

Occasionally, surgery is done to remove the tumor first; the diagnosis is made after the tumor has been examined in a laboratory.

Some studies have examined the use of CT scanning to try to diagnose lung cancers earlier. Although CT can detect abnormalities in the lungs before they cause symptoms, the abnormalities are not always cancer. In addition, studies have not shown that this type lung cancer screening improves patients' prognosis or survival.

After the cancer has been diagnosed, it is assigned a "stage." The stages of squamous cell carcinoma reflect the tumor's size and how far the cancer has spread. Stages I through III are further divided into A and B categories.

  • Stage I tumors are small and have not invaded the surrounding tissue or organs.

  • Stage II and III tumors have invaded surrounding tissue and/or organs and have spread to lymph nodes.

  • Stage IV tumors have spread beyond the chest.

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From Health A-Z, Harvard Health Publications. Copyright 2007 by the President and Fellows of Harvard College. All rights reserved. Written permission is required to reproduce, in any manner, in whole or in part, the material contained herein. To make a reprint request, contact Harvard Health Publications. Used with permission of StayWell.

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