A chest X-ray is the first step in evaluating lung cancer. Normal X-ray procedures give a good picture of the chest cavity, but a CT scan (an advanced X-ray system) is usually done to show the lung mass, lymph nodes and the rest of the chest cavity in much greater detail. These X-rays may help evaluate the extent of a lung mass and suggest the likelihood of cancer. A diagnosis of lung cancer, however, requires a biopsy.
An MRI (magnetic resonance imaging) may be part of the evaluation for a lung mass. It is especially useful in evaluating the brain and bones, but it does not visualize the lung well.
A PET scan is a relatively new nuclear medicine technique that may be very helpful in evaluating and identifying the stage of a lung mass. If a lung mass "lights up" on the PET scan, it is a lung cancer most of the time. If the mass does not light up on the PET scan, it is not likely to be a cancer. The test also evaluates the entire body to see search for any evidence that the tumor has spread to lymph nodes or other areas of the body.
Although X-rays may suggest the presence of cancer, a biopsy is needed to make the diagnosis. Biopsy is the removal and examination of biological tissue, cells or fluids. A biopsy may be performed in several ways.
Sputum - A patient can cough up a sputum sample to look for cancer cells. Sputum cytology will diagnose 75% of tumors located in the bronchi (windpipes), but only 25% of tumors located toward the edge of the lung. Most lung cancers are not in the windpipes so most cancers are not diagnosed by sputum tests. If the test does not diagnose cancer, there is no guarantee that cancer is not present.
Needle biopsy - A needle biopsy is a technique in which a radiologist anesthetizes the skin and inserts a needle through the chest into a lung mass. This is usually done in the radiology department with a CT scan to accurately direct the needle. This will diagnose 60 to 90% of lung cancers, depending on the size and location of the cancer. Even under the best circumstances, however, a needle biopsy sometimes fails to diagnose some masses that are actually lung cancers. Therefore, if the test does not diagnose cancer, there is no guarantee that the lung mass is benign (not cancer).
Bronchoscopy - Another method to obtain tissue is flexible bronchoscopy. The bronchoscope is a flexible, hollow tube that is inserted through the mouth or nose and into the bronchi (windpipes). The procedure may be performed under light sedation or a general anesthetic. If a tumor is seen in the windpipe, a tissue sample can be obtained. Light bronchoscopy is a special bronchoscope that uses a special type of light to identify cancers not seen with standard light. Most lung cancers are not visualized with the bronchoscope because they are located toward the edge of the lung, rather than in a major bronchus.
EndoBronchial UltraSound (EBUS) - EBUS is a technique with a special bronchoscope that has an ultrasound on the tip. The ultrasound identifies lymph nodes on the outside of the windpipes. The ultrasound then helps the surgeon pass a needle into the lymph node to determine if there is cancer in the node. This can both make a diagnosis and stage a lung cancer.
Mediastinoscopy - Cervical mediastinoscopy is a surgical procedure that is done under general anesthesia in the operating room. Through a one-inch incision in the neck, the surgeon follows the windpipe into the chest to remove lymph nodes. This procedure can be done on an outpatient basis. It is an important test because it not only can diagnose a lung cancer, but it also indicates the extent of the tumor so it helps determine the proper treatment. This is most often an outpatient procedure. Sadly, in the United States, about half of the mediastinoscopy procedures produce no lymph nodes for biopsy. There should be several nodes removed with this procedure. (Little)
Wedge Resection - A surgical biopsy may be necessary to determine whether or not a lung mass is a cancer. This requires hospital admission and a general anesthetic. Often, the biopsy can be obtained with three small (half-inch) incisions in a procedure called thoracoscopy or video-assisted thoracic surgery (VATS). A camera is placed through one of the incisions, while the pathologist places surgical instruments through the other incisions to remove the lung mass for examination. If cancer is found, then a complete cancer operation is performed while the patient is still asleep.
Small cell cancer accounts for about 25% of all lung cancer. It is staged as either limited disease (confined to the chest) or extensive disease (spread outside the chest). Small cell cancer is usually treated with chemotherapy and radiation therapy. It is rarely treated with surgery because by the time it is diagnosed it has usually spread to other parts of the body, even if the tests do not prove it.
There are four stages of non-small cell lung cancer. This staging system is important for determining the prognosis and treatment for lung cancer.
- Stage I is a cancer confined to the lung and usually treated with an operation.
- Stage II cancer that has spread to lymph nodes near the tumor and within the lung is usually treated with an operation, but may be subsequently treated with chemotherapy and/or radiation.
- Stage III cancer is confined to the chest, but it has spread more widely through the tissues in the chest.
- Stage IV cancer has spread to other parts of the body, such as the brain, liver or bones.
Evaluation and Staging of Lung Cancer
The staging and evaluation of a lung cancer involves a history and physical examination and several other tests. Knowing the stage of your cancer helps you and your doctor develop a proper treatment plan. Tests will also determine if you have the lung capacity to undergo treatment.
Pulmonary Function Tests - Pulmonary function tests are done to see if the patient has enough lung function so that an operation can be performed safely. The patient breathes into a machine to determine the lung capacity. If the pulmonary function test is good, then a lobectomy is the usual treatment. If the pulmonary function is not adequate, there are other surgical and non-surgical treatment options.
Brain CT Scan or MR - Lung cancer may travel to the brain so imaging of the brain is performed if the patient has headaches or neurologic symptoms, weight loss, or appears to have a more advanced stage tumor. If there are no symptoms and the tumor appears to be early stage, this is often not done because the chances of finding the tumor in the brain is low.
CT Scans - A CT of the chest is needed to evaluate the tumor. The surgeon needs to look at the tumor to determine the location so the surgeon knows where to resect and the relation of the tumor to surrounding structures to determine the extent of the resection needed to remove the tumor (just the mass, a section of the lung or the entire lung).
PET Scan - Parts of the body with an active metabolism (such as the brain, liver, tumors) absorb more glucose than other parts of the body so Fluorodeoxyglucose is injected to identify these areas. This test is often used to evaluate a mass in the lung and determine if there is spread elsewhere. In general, if a mass in the lung lights up on the PET scan, there is an 80 to 90% chance that it is cancer. A false positive test can occur if the mass is inflammatory or infection. If the lung mass does not light up on the PET, the chances of the mass being cancer are only 5%. False negative tests occur if the mass is small (<1 cm) or a low grade, slow growing tumor, such as broncho-alveolart cancer (BAC, now known as AIS). The PET scan evaluates the mediastinum (middle of the chest) to see if the lymph nodes are involved. False positive tests occur up to 25% of the time; this may be due to infection, inflammation, or anthrocosis. False negative tests occur if the area of tumor on the lymph node is small (<1 cm). Nodes that are positive on the PET generally need to be biopsied to determine if there really is tumor there.
Bone Scan - A bone scan or a brain scan, may be done to see if the tumor has metastasized (traveled) to other parts of the body.