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Non-small cell lung cancer

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of non-small cell lung cancer (NSCLC).

Alternative Names

Lung cancer -  non-small cell; NSCLC

Diagnostic Tests

Chest X-Rays. In a small percentage of cases, a routine chest x-ray reveals the first signs of lung cancer. Usually, however, symptoms of existing lung cancer, such as coughing, chest pain, and blood in the sputum, will lead to a chest x-ray. If non-small cell lung cancer is present, chest x-rays may show lesions (damaged or abnormal tissue) in the center of the lung, cavities formed by squamous cell carcinoma, or lace-like pattern of cells spreading through the lungs. By the time lung cancer is diagnosed by chest x-rays, however, it has often spread so far that it cannot be surgically cured. Four major studies found no survival benefits in early detection from chest x-rays and sputum screening. Regular screening for lung cancer using x-rays is therefore not currently recommended.

Computed Tomography. Computed tomography (CT), particularly the specific technique called low-dose spiral (or helical) CT, is more effective than x-rays for detecting cancer in patients with suspected lung cancer. It is the standard imaging procedure for determining if and where the cancer has spread (metastasized). Surgeons also use CT scans to evaluate patients before lung surgery.

The use of helical CT for early screening is still controversial. Studies of CT scans in smokers suggest that early screening will detect about 2% of lung cancers, and most of these in early stages. In the studies, 62 - 82% of the patients with stage 1A cancer (when the tumor has not spread yet) were still alive at 5 years. Neither study, however, was controlled (compared with other groups; for example, non-smokers). The survival figures were likely to be higher than in actual practice.

The evidence regarding the survival benefits of early detection is not clear. Many experts are highly opposed to widespread screening for lung cancer. Some evidence, for example, suggests that lung cancer cells in non-small cell lung cancer are often very aggressive at microscopic levels (before a tumor is formed). If this were true, the cancer would be highly likely to have already spread, long before it was visible with CT scans. Moreover, some studies have found no association between tumor size at the time of diagnosis and survival times. On the other hand, some abnormalities detected by CT scans may actually be innocent, and such patients might be more likely to die from aggressive treatments than from the disorder itself.

It should also be noted that about 98% of abnormalities seen on CT scans turn out to be benign. Even after rescreening, many scans will show suspicious areas that turn out to be harmless but will require invasive and expensive biopsies. Additional experience with CT scans, however, may allow experts to better determine which abnormalities are likely to be benign.

High-risk individuals who are still interested in early screening with CT scans should ask their doctor about available clinical trials.

Other Imaging Tests for Staging and Tracking Cancer

Computed tomography is the standard imaging procedure for determining if and where the cancer has spread (metastasized). Other imaging tests, however, may be useful for staging and tracking lung cancers (staging means finding out how advanced the cancer is).

Positron Emission Tomography. Positron emission tomography (PET), specifically a technique known as FDG/PET, is the most accurate noninvasive test for detecting early lung cancer. It is also the best imaging technique for staging lung cancers, not only those located in the lungs, but also those that have spread, particularly into the space between the two lungs (the mediastinum ). With this imaging test, the patient is first injected with a specially formulated liquid sugar (called FDG), and then viewed with a machine that records energy given off by tumor cells.

PET is expensive and not widely available. However, its supporters suggest that it may prevent many unnecessary surgeries by identifying patients whose cancer has advanced past the stage at which surgery is helpful. There is some evidence that FDG/PET scan can detect a metabolic (processing) response to treatments that may help predict the outlook for the patient.

Scintigraphy . Scintigraphy is an imaging procedure in which patients are administered low-level radioactive agents that bind to cancer cells, which then can be tracked by special cameras to reveal the cancer cells' location and intensity. Agents selected are those that can best bind successfully with specific tumor types. For example, a 2001 study of the binding agent 111In-DOTA-LAN demonstrated excellent results in identifying non-small cell lung tumors. This study further suggests the possibility of using such highly-targeted binding agents as lung cancer treatments.

Magnetic Resonance Imaging. Magnetic resonance imaging (MRI), an imaging procedure that uses radio wave energy, is frequently used instead of CT scanning to locate brain and bone metastases that can be associated with lung cancer.

Biopsy Procedures

Biopsies of lung tissue are needed confirm lung cancer. This requires invasive procedures that may vary from simple needle aspiration to chest surgery.

Needle Aspiration. Sometimes, a biopsy specimen is obtained by inserting a needle between the ribs, and then guiding it with the use of computed tomography scans, ultrasound, or fluoroscopy (a device allowing an x-ray view). Specific techniques include transbronchial or transthoracic needle aspiration (TBNA or TTNA) or endoscopic ultrasound-guided needle aspiration (EUS-NA). Their use depends on how much of the area can be observed with less invasive imaging methods. There is a 5 -10% risk for bleeding or collapsed lung with needle aspiration.

Thoracoscopy. Thoracoscopy is usually very effective for diagnosing cancer in the outer areas of the lungs, or those involving the pleura (membrane surrounding the lungs). This is a surgical procedure that uses a fiber-optic tube to view the area:

• The procedure requires general anesthesia.
• The surgeon passes surgical instruments and a fiber-optic tube through a small incision in the chest. The tube has a camera in it, which allows the surgeon to look at the lungs on a video screen.

Bronchoscopy. To locate cancer that develops in the central areas and major airways of the lung (usually squamous or small cell cancer), bronchoscopy is typically performed. The procedure is done as follows:

• The patient is given a local anesthetic, supplementary oxygen, and sedatives.
• The doctor inserts a bronchoscope, a hollow flexible tube often containing a fiber-optic light source, into the lower respiratory tract through the nose or mouth.
• The tube acts like a telescope into the body, allowing the doctor to see the windpipe and major airways. In a procedure called fluorescence bronchoscopy, the doctor injects the patient with a drug that makes cancer tissue appear red when exposed to laser light from the bronchoscope.
• The surgeon removes specimens for biopsy, ideally using a combination of techniques that include cutting tissue, brushings, and a washing process called bronchoalveolar lavage (BAL). BAL involves injecting saline through the bronchoscope into the lung and then immediately suctioning the fluid back through the hollow tube of the bronchoscope; the fluid is then analyzed in the laboratory. Both brushing and washing procedures may be very valuable additions.

Advances in this procedure, such as laser-induced fluorescence endoscopic bronchoscopy, may improve early detection of cancer.

Bronchoscopy is usually very safe, but complications can occur; they include allergic reactions to the sedatives or anesthetics, asthma attacks in susceptible patients, and bleeding. Fever may follow the procedure.

Mediastinoscopy. Mediastinoscopy uses a tube inserted between the lungs to locate the appropriate areas for biopsy. It is performed if the physician suspects that cancer has spread to nearby lymph nodes but has not yet metastasized.

Laboratory Tests

Sputum Analysis for Presence of Cancer Cells. Some experts are now recommending an analysis of coughed-up sputum as a useful and cost-effective measure for identifying cancer cells, particularly those located in central areas of the lung. However, although sputum analysis appears to be as accurate as any other screening test currently conducted, it may miss cancers such as adenocarcinoma, which form in mucus-producing cells typically in the outer portion of the lungs. If a sputum analysis does not show cancer cells, but other signs of lung cancer are present, including blood in the sputum and suspicious areas on X-rays, then other tests are performed.

Biomarkers. Biologic markers, called biomarkers, are high levels of substances that are released by tumors and indicate the presence of specific cancers. Biomarkers can be found in sputum, blood, and tissue samples. They can include enzymes, hormones, amino-acid compounds, antigens (identified by antibodies that specifically target them), growth factors, and other chemicals. Some biomarkers may prove to reveal the presence of cancer cells before they are evident on CT scans or other imaging tests. For example, genetic mutations, notably K-ras and p53, can now be detected in cells found in sputum, or cells taken during bronchoscopy. Such mutations occur only with cancerous changes and may enable early detection. Other markers that prove to be important for predicting aggressive cancers are high levels of matrix metalloproteinase (MMP9) and vascular endothelial growth factor (VEGF), which are compounds involved with angiogenesis (the process in which blood vessels serving the tumor develop).

Other Tests

As part of the doctor's initial examination, patients may have a pulmonary function test to evaluate lung health and capacity. In addition, since the heart and lungs are often involved in complications following lung cancer surgery, the doctor may be especially interested in taking a complete history of those systems in patients who might need surgery.

• Review Date: 6/30/2006
• Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.

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