Physical Examination
Patients who are suspected of having lung cancer should undergo a thorough physical examination. In addition, the physician may ask the patient to provide a sample of sputum (matter from the throat and lungs, which is spit out through the mouth). The sputum sample will be sent for testing to see if it contains bacteria, other infectious organisms, or cancer cells; cancer cells may be present in the sputum in certain types of lung cancer. If sputum analysis does not provide a definite diagnosis, more tests will be needed. The physician may want to perform one or more of the following tests.

• Chest radiograph (x-ray) is used to detect enlarged lymph nodes in the chest or a localized mass in the lungs.
• Computed tomography (CT or "CAT" scan) is a computer-assisted technique that produces cross-sectional images of the body.
• Magnetic resonance imaging (MRI scan) is a diagnostic method in which hydrogen ions within the body (and/or specific body parts) are excited by exposure to a magnetic field. The resulting signals are processed by a computer to create an image of the chest to define the location and extent of lung involvement.
• Bronchoscopy is a visual examination of the windpipe and lung branches performed by a pulmonologist (respiratory disease specialist) using a flexible scope. Bronchoscopy may involve brushings (using a small, brush-like device to gather cells from the tissue lining the respiratory system), washings of the respiratory tissues for cell analysis, and biopsy (removal and examination of small amounts of tissue). If the bronchoscopy is still unrevealing, or "negative," a needle biopsy may be performed.
• Needle biopsy, with CT-guidance, may be performed on suspicious areas in the lungs or pleura. Fine needle aspiration (FNA) uses a slim, hollow needle that is attached to a syringe. The needle is inserted into the suspicious mass and it is pushed back and forth to free some cells, which are aspirated (drawn up) into the syringe and are smeared on a glass slide for analysis. Large needle, or core biopsy, uses a large-bore needle to obtain a tissue sample for analysis.
• Bone scan may also be performed to rule out suspicions of metastasis to the bones. Metastasis is the process wherein cancerous cells break away from the original tumor, travel, and grow within other body parts.

If there is no evidence of metastasis, the patient may then undergo mediastinoscopy, a surgical inspection of the mediastinum (the tissues and organs of the middle chest, e.g., the heart and large vessels, windpipe, etc.). A small flexible device with a camera, called an endoscope, is inserted into the chest via an incision at the top of the sternum (breastbone), and the chest cavity is then examined.

The mediastinal lymph nodes usually are removed during this procedure. If the mediastinal lymph nodes are "negative" (do not contain any cancer cells), the patient may be a candidate for surgery. However, if mediastinal lymph nodes are "positive" (contain cancer cells) or are abnormally large on imaging studies (suggesting tumor involvement), the patient is not considered to be a surgical candidate.

Additional blood tests may be performed to look for lung cancer "markers" - that is, elements in the blood that are associated with the presence of lung cancer. For example, lung cancer may be indicated by abnormalities in the following.

• PTH (parathyroid hormone) - Blood levels of PTH or PTH-related protein may help to distinguish lung cancer from cancer of the pleura or other diseases.
• CEA (carcinogenic antigen) - a cancer-specific immune system protein that is present in many adenocarcinomas, including lung adenocarcinoma. Increased preoperative levels of CEA usually suggest a poor prognosis. A CEA level greater than 50 may indicate advanced stage lung cancer and should discourage treatment by resection.
• CYFRA21-1 (cytokeratin fragment 19) - a protein marker of lung cancer.