Lung Cancer Diagnosis
Early diagnosis of lung cancer is difficult because noticeable symptoms don’t usually show up until the disease is more advanced. You may have felt fine, and your diagnosis was a surprise to you—and your doctor. Or you may have had signs or symptoms of lung cancer during a routine physical examination, and your doctor ordered tests that found the cancer. Many lung cancers are found coincidentally with a chest X-ray following work up for an unrelated surgery or illness. There are certain tests that must be performed to confirm the diagnosis of lung cancer.
In addition to a history and physical examination, there are diagnostic tests for people with suspected lung cancer. These tests consist of laboratory testing, radiology tests, tissue biopsies and/or sampling of pleural fluid. The understanding of all test results helps the lung cancer team determine tumor type, clinical stage and individual treatment planning. Following are some of the tests your clinical team may order.
Imaging Studies - Clinical Diagnosis
- Chest X-ray. The most common test used when lung cancer is suspected is the chest X-ray, which uses small amounts of radiation to take a picture of inside your chest, including your lungs. Some tumors around your lungs can be visible with chest X-ray. However it should be noted that a chest x-ray cannot detect small tumors only visible on CT scan.
CT and MRI scans. CT (computed tomography) and MRI (magnetic resonance imaging) use computers to produce detailed, three-dimensional images that help diagnose lung cancer and can determine the size, shape, and location of the tumor. If symptoms of lung cancer are present, a contrast-enhanced CT scan is recommended. Both CT and MRI scans are useful in determining if lung cancer has spread to other areas of the body. For more information on St. Joseph Hospital's Spiral CT Lung Screening program,
- PET scans. PET (positive emission tomography) scans may give a more accurate picture of the stage of non-small cell lung cancer (NSCLC), often as a follow-up to other tests or to diagnose recurrent disease. However there is no evidence that PET scan can replace pathological staging of lymph nodes through biopsy.
- PET/CT. Most recently PET/CT scans have become valuable in restaging of NSCLC lung cancer following treatment. PET captures images of changes in the body’s metabolism caused by the growth of abnormal cells. These abnormal cells will reveal “hot spots” that may be abnormal growth of tumors. It should be noted that “hot spots” could be reflective of other conditions such as inflammation or infection. CT images simultaneously allow physicians to pinpoint the exact location, size and shape of the diseased tissue or tumor. The PET and the CT images are fused together. The CT scan shows anatomical detail and the PET scan provides the metabolic activity of the tumor.
- Sputum Cytology. In this test your sputum, which is the mucus you cough up, is collected and examined under the microscope to look for cancer cells. The most accurate way to do this is to collect and analyze early morning mucus for 3 days.
Biopsy Procedures - Pathologic Diagnosis
- Biopsy. The previously mentioned tests allow your treatment team to view the inside of your body. However, they do not test the tumor for the presence of cancer cells. Therefore these tests do not provide absolute proof that you have cancer. To confirm the presence of cancer (pathologic diagnosis), a sample of tissue from the tumor is needed. A biopsy is the term used for the removal and examination of a tissue sample to determine if it is cancerous. Biopsies are performed in different ways depending on the location and size of the tumor.
- Bronchoscopy. A bronchoscopy allows the doctor to see inside of the lungs and airways using a hollow tube (called a bronchoscope) and inserting it into the mouth, down the windpipe (trachea) and into the lungs. A small camera on the end of the bronchoscope takes pictures and sends them back to a monitor so the doctor can see the tissue. A small tool at the end of the scope is then used to remove a sample of the tissue from the tumor. In addition, bronchial lavage or washing is a technique used with bronchoscopy. Direct brushing or washing of the abnormalities is used to determine a diagnosis.
- Transthoracic needle aspiration. The doctor uses a needle to penetrate the chest wall to take a sample of tissue within the lung. This procedure is used for tumors close to the chest wall. This is usually performed with conscious sedation as an outpatient.
- Cervical Mediastinoscopy. A small tube is passed through an incision at the top of the breastbone, in front of the trachea and into the mediastinum. A small camera at the end of the tube allows the doctor to see the tissues. This procedure determines whether cancer has spread to lymph nodes near the trachea—one of the first places lung cancer is likely to spread. This procedure requires a local and general anesthesia but can usually be done on an outpatient basis.
- Thoracentesis. If fluid is collecting between the lungs and the chest wall, this procedure is used to extract some of the fluid through a needle to see if cancerous cells are present. This procedure can be performed with local anesthesia as an outpatient.
- Video-assisted thoracoscopy. Under general anesthesia, a tube containing a small television camera is inserted between the ribs through a small incision in the skin, so the doctor can see the tumor. This procedure removes a larger portion of the tumor rather than taking a small tissue sample. This procedure may require a short hospital stay.