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Lung Cancer Diagnosis


Tests

When lung cancer is suspected, a series of tests are conducted to confirm the disease and to determine how widely the cancer has spread (staging). The major tests include:

X-rays: A chest x-ray is frequently ordered as a first step in diagnosis. An x-ray is a two-dimensional picture that can help to locate a tumor. Once a tumor can be seen on x-ray, however, it may have already spread into the lymph nodes or elsewhere in the body. A negative chest x-ray does not always mean that there is no lung cancer present. If the tumor is small it may not be visible on an x-ray.

Computed tomography imaging (CT scan) or, on occasion, magnetic resonance imaging (MRI): These tests may help your doctor confirm a diagnosis based on a chest x-ray. CT scans and MRIs are tests that use computerized pictures to show very detailed three-dimensional images of the body. They can show the size, shape, and location of a tumor. These tools are also useful in finding out if the tumor has spread from the lung to lymph nodes or other organs in the chest or to other parts of the body.

Positron emission tomography: In this procedure, the patient is injected intravenously with a small amount of radioactive sugar that is highly absorbed by cancer cells and detected by a special camera. The technique is very sensitive and even very small malignant tumors can show up easily on the PET scan. The test can determine if the cancer has spread to lymph nodes or other distant places because PET scans the entire body and can be used in place of several x-rays. It is also helpful in telling whether a shadow on your chest x-ray is cancer. Most insurance companies cover expenses for PET imaging and in Dec. 2000 the Health Care Financing Administration (HCFA) expanded Medicare coverage for diagnosis, staging, treatment and for monitoring recurrences.

Bone scans: A small amount of radioactive tracer is injected into a vein and accumulates in areas of bone that may be cancerous. Then a gamma camera is used to scan the body to detect where bone formation is occurring faster than the surrounding bone in response to injury of the bone by cancer. Bone scans are commonly done in patients with lung cancer when symptoms or other test results suggest that the cancer has spread to the bones.

Lung biopsy: A biopsy is a test in which tissue is removed from the suspected tumor and examined under a microscope to see if cancer cells are present. A biopsy is necessary for the doctor to confirm a cancer diagnosis, and to identify the specific type of cancer and its stage. There are two types of biopsy. Needle biopsy is just like it sounds: a needle is inserted through the chest wall to take a sample of tissue from a known tumor after it has been located by chest x-ray, CT scan or fluoroscopy (fluoroscopy is like an x-ray, but the image is viewed on a screen in real time rather than on film). The other kind is surgical biopsy. In this test, the chest wall is opened to remove a part or all of the tumor. Tissue samples are examined by a pathologist, who will be able to provide information about the type of cancer, if any, that is present and the stage of the cancer.

Bronchoscopy: A procedure in which a flexible lighted tube (bronchoscope) is inserted through the nose or mouth, and into the airways to collect bronchial and/or lung secretions or to biopsy for tissue specimens. Sedation is required because the procedure can be uncomfortable.

Mediastinoscopy: Under general anesthesia, a small cut is made in your neck to allow a hollow lighted tube to be inserted behind the sternum (breast bone). Through this hollow tube specialized instruments can be placed to sample tissue from the mediastinal lymph nodes (along the windpipe and the major bronchial tube areas). Microscopic examination can reveal if cancer cells are present.

Mediastinotomy: A surgical procedure that opens the chest cavity to remove samples of mediastinal lymph nodes while the patient is under general anesthesia. More lymph nodes can be sampled in this way than with the mediastinoscopy procedure.

Thoracentesis: A needle is placed between the ribs to drain accumulated fluid around the lungs (called pleural effusion) and examined microscopically for the presence of cancer cells. Malignant pleural fluid can indicate that cancer has spread to the delicates membranes that cover the lungs (called pleural membranes) Fluid accumulation can also prevent the lungs from filling with air, so thoracentesis can also help improve the patient's breathing.

Thoracoscopy: A procedure that views the space between the lungs and the chest wall using a thin, lighted tube connected to a video camera and monitor. Like thoracentesis, this examination checks whether a pleural effusion is the result of cancer mestastasis to the pleural membranes or to some other, benign condition such as heart failure or an infection.

Bone marrow biopsy: A sample of bone about 1/16 inch across and 1 inch long (usually from the back of your hip bone) is removed after the area has been numbed with local anesthesia. The sample is checked for cancer cells under the microscope.


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