Non-Small-Cell Lung Cancer (cont.)
Koyamangalath Krishnan, MD, FRCP
Exams and Tests
Medical evaluation and tests
The symptoms of lung cancer can be caused by many different medical conditions. Even a chest x-ray film that shows what looks like a tumor is not enough to make the diagnosis of lung cancer. The health care provider’s job is to gather all available information and to make the diagnosis. Correct and prompt diagnosis is essential so that appropriate treatment can be started as soon as possible.
The first step in the evaluation is the medical interview. The health care provider asks the patient questions about symptoms and when they started, current or past medical problems, medications taken, family medical problems, work and travel history, and habits and lifestyle. This is followed by a thorough physical examination.
The remainder of the evaluation focuses on confirming the presence of lung cancer and staging the tumor. Although primary care providers are able to conduct this evaluation, they may prefer to refer the patient a specialist. At any time during this evaluation, the primary care provider may refer the patient to a surgeon or to a specialist in lung diseases (pulmonologist) or cancer (oncologist).
No blood test can confirm that a patient has lung cancer. Blood tests are performed to check the patient’s general health, to rule out other conditions that might cause similar symptoms, and to detect certain paraneoplastic syndromes. The usual blood tests include the following:
- Complete blood cell counts
- Liver and kidney function tests
- Blood chemistry and electrolyte levels
Respiratory symptoms are usually evaluated with a chest x-ray film, CT scan
of the chest, or both. X-ray films are limited in the amount of detail they provide, but they clearly show some tumors. CT scans shows much greater detail in a 3-dimensional format. A CT scan
is needed if the x-ray film findings are not definitive. If imaging studies show evidence of a tumor, further testing is needed. Other tests
: Sputum is mucus
in the lungs. Sputum is the body’s natural system for removing small particles and contaminants from the airways. Many people, especially those who smoke, produce sputum when they cough. In some cases of lung cancer, tumor cells are sloughed off into the sputum and can be detected by cytologic (cell) testing. For this test, the patient is asked to cough, and the sputum is collected and examined.
- This simple test, if the result is positive for tumor cells, confirms the diagnosis of cancer. A result negative for tumor cells, however, does not confirm that no cancer is present.
- In either case, further testing is needed: if positive for tumor cells, to determine the type of cancer; if negative for tumor cells, to seek definitive evidence of whether a tumor is present.
: This is the use of a device called an endoscope
to view the lungs directly. An endoscope is a thin tube with a light and a tiny camera on the end. The endoscope is inserted through the mouth
into the bronchus
) and down to the lung. The camera transmits pictures of the inside of the patient’s airways that can be viewed on a video screen.
- Bronchoscopy allows the doctor to look directly at the tumor (if one is present). This allows the doctor to determine the tumor’s size and the extent to which it is blocking the airway.
- The bronchoscope can also be used to collect a biopsy. A biopsy is a small sample of the tumor or any abnormal-appearing lung tissue, for further testing.
- The biopsy is examined under a microscope by a pathologist, a specialist in diagnosing diseases in this way. The pathologist confirms whether the mass is cancer and, if so, the type of cancer.
- This technique is also used to examine the area around the main airway, between the lungs in the middle of the chest (mediastinum). The cancer can infiltrate the lymph nodes in this area. The endoscope is inserted through a small incision just above or to the side of the breastbone. This technique is called mediastinoscopy. Enlarged lymph nodes and other abnormal tissues can be removed during this procedure.
CT-guided biopsy: This procedure involves a CT scan to guide the removal of a biopsy. It is used for tumors that cannot be reached with a bronchoscope, usually because they are in the outer part of the lung. Again, this material is examined to confirm the presence of a tumor and to determine the type of tumor.
Biopsies from other sites: Material can also be obtained from other sites with abnormalities to confirm the diagnosis. These sites include enlarged lymph nodes or liver and collections of fluid around the lung (pleural effusion
) or heart
Staging is a system of classifying cancers based on the extent of the disease. In general, the lower the stage
, the better the outlook for remission
and survival. In NSCLC, staging is based on the size of the primary tumor, the number of cancerous lymph nodes, and the presence of any metastatic tumors. Accurate staging is essential in NSCLC because the stage of the cancer determines which treatment may offer the best results.
For people with lung cancer, the first step is to undergo a staging evaluation. The patient’s medical team cannot make recommendations for the best treatment until they know the cancer’s exact stage.
This evaluation includes many of the tests already described. Other tests are as follows:
- CT scan of the chest and upper abdomen: The purposes of this scan are to measure the exact size of the primary tumor, to look for enlarged lymph nodes that may be cancerous, and to look for signs of metastatic disease in the liver and adrenal glands.
- CT scan or MRI of the brain: This is needed only if the patient is experiencing neurologic symptoms that suggest that the cancer has metastasized to the brain.
- Positron emission tomography (PET) scan: This scan detects cancer cells throughout the body based on the rate they use glucose (sugar); this rate is higher than that of normal cells. PET scan is available only at some large medical centers.
- Bone scan: This test, formally known as scintigraphy, looks for metastasis to the bones. A harmless radioactive substance is inserted into the bloodstream. It concentrates in areas where the infiltrating cancer has weakened the bone. A scan of the entire skeleton highlights these areas. Generally, this test is performed only if the patient is experiencing bone pain or other signs of bony metastasis.
- MRI of the spine: MRI is the best test for compression of the spinal cord. This happens when the metastatic disease and the collapse on the spinal cord weaken the bones of the spine. This is a serious complication of lung cancer. It usually causes pain in the neck, back, or hip. Compression of the spinal cord can also cause numbness or paralysis in the arms, legs, or both; problems controlling bladder or bowels; and other problems.
The stage is determined by a combination of the following 3 characteristics:
- T - Size and extent of primary tumor (X,1,2,3,4)
- N - Involvement of lymph nodes in the region of the lungs (0,1,2,3)
- M - Metastatic involvement
For each tumor, a number is assigned for each of the 3 letters—for example, T2N1M0. These 3 numbers determine the stage. NSCLC has 4 stages, designated I, II, III, and IV. Stages I-III are subdivided into A and B subtypes. The stage groupings are as follows:
- IA: T1N0M0; The tumor is limited to the lung, and the tissue around the tumor is normal.
- IB: T2N0M0; The tumor is limited to the lung but is larger than in stage IA. The tissue around the tumor is normal.
- IIA: T1N1M0; The tumor has spread to the area around the lung, such as lymph nodes, the chest wall, the diaphragm, or the sacs surrounding the lung or heart.
- IIB: T2N1M0, T3N0M0; This stage is similar to stage IIA but the tumor is larger or nearby lymph nodes are involved.
- IIIA: T1-3N2M0, T3N1M0; The tumor has spread to the lymph nodes in the mediastinum, on the other side of the chest, or in the lower neck.
- IIIB: Any T4 or any N3M0; This stage is similar to stage IIIA but the tumor is larger.
- IV: Any M1; Tumor has spread to another section of the lungs or elsewhere in the body.
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