Researchers Find Less Invasive, Highly Accurate Methods

Using two different endoscopes together is better than using one to stage lung cancer, and is also much more precise and less invasive than the surgical method now most commonly used, researchers at Mayo Clinic in Jacksonville, Fla., report in the Feb. 6 issue of the Journal of the American Medical Association.

This new technique, which uses two small flexible tubes, one of which is inserted into a patient’s esophagus to access lymph nodes in the back of the lungs while the other is placed into the trachea, or airway, to reach nodes at the front and sides, was 93 percent accurate in finding malignant lymph nodes in a group of 138 patients. This is substantially more precise than all other lung cancer staging methods now in use today, say the researchers, who tested three different methods of non-invasive staging in their study.

“Both scopes together found more malignant lymph nodes than did the use of a single endoscope,” says the study’s lead investigator, Michael Wallace, M.D., M.P.H., Professor of Medicine at Mayo Clinic, Jacksonville, Fla. “Doing both procedures at once takes little time, requires only a mild sedative, and patients go home the same day.”

The combination technique was pioneered by Wallace, a gastroenterologist, and study co-author Jorge Pascual, M.D., a pulmonologist. Since the researchers have seen how effective this method is, the two tests are now used routinely at Mayo Clinic Jacksonville to stage lung cancer patients. The researchers are among the first to publish studies examining use of the two scopes, and this study is the largest and most comprehensive to date.

Lung cancer is the most common cause of cancer death. Treatment of the disease depends on whether the cancer has spread outside the lungs, and in order to know that, physicians need to biopsy (remove a small piece of tissue for examination) the lymph nodes that are adjacent to the organ. Patients whose cancer has not spread can be treated with potentially curative surgery to remove lung tumors, and chemotherapy and radiation are used for patients whose cancer has spread. Staging of cancer is the process by which doctors determine whether a cancer has spread to other sites such as lymph nodes or other organs, and thus which is the most appropriate treatment.

Shortcomings in each method of staging

The traditional staging technique is to first perform a CAT scan of the lungs to find enlarged lymph nodes. PET scans are also used to determine if a cancer has spread, but both CT and PET have limits, Dr. Wallace says. They can only determine if a lymph node is enlarged or has a high metabolism; features which suggest, but do not prove that cancer is present. Most doctors, including the American College of Chest Physicians, now recommend that CT and PET scans be confirmed with a biopsy of the lymph nodes.

Traditionally, such a biopsy could only be done surgically by inserting a rigid steel scope into the chest through a surgical opening above the breast bone. The scope is maneuvered to lymph nodes of interest and a small piece of tissue is taken to look for signs of cancer. This procedure, known as a mediastinoscopy, can only access lymph nodes on the front or sides of the lungs, Dr. Wallace says. Studies summarized by the American College of Chest Physicians have shown it is approximately 78 percent sensitive – that is, of all patients whose lung cancer has spread to lymph nodes, this technique can pick up, at most, 78 percent of them, he says. Another limitation of mediastinoscopy is the need for general anesthesia, and the small but real risk of major complications, Dr. Wallace says.