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 a 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 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.

CT stands for computerized tomography. In this procedure, a thin x-ray beam is rotated around an area of the body. Using very complicated mathematical processes called algorithms, the computer generates a 3-D image of a section of the body. CT scans are very detailed.

The use of helical CT for early screening is still controversial.

Evidence to date has not proven a survival benefit of using CT scans to screen people without symptoms. 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 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.

It should also be noted that about 98% of suspicious areas 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. In these cases, patients are more at risk from aggressive tests than from the disease itself. 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 also 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 can diagnose lung tumors as small as 1 centimeter with very high accuracy. PET works best when used with CT scans.

PET is a good imaging technique for staging lung patients thought to have early stage lung cancer after other testing. These patients are considered candidates for surgery intended to cure. Performance of a PET scan for this group has been shown to prevent unnecessary surgical procedures by identifying previously undetected spread of the cancer elsewhere in the body.

With this imaging test, the patient is first injected with a specially formulated, radioactive liquid sugar (called FDG), and then viewed with a machine that records energy given off by cells that absorb high levels of FDG, such as lung tumor cells.

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 tumors that have spread from the lung.

Biopsy Procedures

Biopsies of lung tissue are needed to 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 CT 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. Bronchoscopy can help locate cancer that develops in the central areas and major airways of the lung (usually squamous or small-cell cancer). The procedure is done as follows:

• The patient is given a local anesthetic, 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 combining techniques to 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 to this procedure.

Bronchoscopy is usually very safe, but complications can occur. They include:

• Allergic reactions to the sedatives or anesthetics
• Asthma attacks in susceptible patients
• Bleeding

Patients may develop a fever after 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 spread to other parts of the body.

Laboratory Tests

Sputum Analysis for Presence of Cancer Cells. Analysis of coughed-up sputum performed as a screening test for lung cancer, is often done along with chest x-rays. This method has not reduced death rates. Recent improvements in this screening technique are under study.

Sputum analysis may also be used to diagnose lung cancer in someone with signs of lung cancer. However, it is not 100% accurate. If a sputum analysis does not show cancer cells, 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
• Other chemicals

A number of these biomarkers are being evaluated alone or in combination as either screening tools or as potential markers for the risk of disease progression.

Other Tests

As part of the doctor's initial examination, patients may have a pulmonary function test to evaluate lung health and capacity. The doctor may also take a complete history of the heart and lungs, because they are often involved in complications following lung cancer surgery.