A definitive diagnosis of lung cancer requires that cells be taken directly from the tumor. The manner by which these cells are obtained depends on where they are in the chest. If the tumor is in the center of the chest, near a bronchus or large bronchiole, a sample may be obtained by bronchoscopy. A bronchoscope is advanced down the airway and can be maneuvered through the bronchus to the site of the tumor. The bronchoscope has small surgical instruments in the tip which allow the pulmonologist to take a bit of the tumor for analysis.
On the other hand, if the tumor is in the periphery of the lung, a sample could be reached by using a needle placed through the chest wall. A fluoroscope, which is an X-ray/CT scan hybrid that instantly provides images of the inside of the chest, is used to guide the biopsy needle. When this external approach is possible, the patient can avoid a surgical procedure to diagnose lung cancer.
In some instances, the tumor cannot be reached by bronchoscopy or fluoroscopy. In these cases, a surgical procedure must be performed. The least invasive of these surgical procedures is thoracoscopy. A thoracoscopy is an endoscopic procedure in which a relatively small incision is made in the chest and a thoracoscope (endoscope) is advanced to the tumor. A biopsy is taken for further testing.
In highly inaccessible tumors, an open surgical procedure may be necessary. This open procedure is called a thoracotomy. In a thoracotomy, the chest is opened and the entire tumor can be seen directly. When a thoracotomy is needed for diagnosis, the entire tumor may be removed along with some surrounding lung tissue. If so, pulmonary function tests (such as those that test lung capacity) should be performed ahead of time.
Once a biopsy has been taken, regardless of the means, it is sent to a pathologist. This medical specialist will apply stains and histochemical markers to the sample and examine it under a microscope. This will provide a very accurate lung cancer diagnosis including a determination of the lung cancer type.
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