Minimally Invasive Procedure Effectively Detects and Evaluates Lung Cancer
Endoscopic ultrasound, a minimally invasive procedure in which a camera-tipped scope is inserted down the esophagus, can safely and effectively determine whether masses in or around the lungs are cancerous or benign.
Duke University Medical Center gastroenterologists who analyzed the results of 18 clinical trials have concluded that the procedure should be used routinely to evaluate, or stage, possible malignant masses. The researchers said that if the procedure were universally adopted, almost one-third of possible lung cancer patients would not need additional, more invasive staging procedures.
The key to successfully treating lung cancer is determining the type of cells that comprise the mass and whether or not they have spread. With the endoscopic ultrasound procedure, physicians can sometimes visualize the mass, but more importantly they can determine if there has been spread to adjacent tissues or lymph nodes by inserting a slender needle through the endoscope that "sucks" out a sample from the mass. A pathologist in the procedure room can quickly determine if malignancy is present.
"The results of this analysis should change the way we stage some types of lung cancers," said Frank Gress, M.D., senior member of the research team whose analysis was published in the February 2007 issue of the journal Chest. The analysis was supported by Duke's Division of Gastroenterology and Center for Clinical Health Policy Research.
"The procedure is safe, improves our ability to evaluate and stage certain lung masses and cancers and may even improve the quality of life for these patients," Gress said. "We are hopeful that more centers will adopt this approach as a routine part of lung cancer staging."
The endoscopic technology used for lung cancer staging is the same as that used for 20 years by gastroenterologists to view the lining of the esophagus, stomach, small and large intestine during an endoscopy procedure. With the added use of ultrasound, which operates much like the technology used by obstetricians to view a baby in the womb, gastroenterologists can look at structures beyond the wall of the intestine, such as the pancreas, gall bladder and the bile duct. Since the mid-1990s, gastroenterologists began to use the same approach to view structures beyond the walls of the esophagus, such as lymph nodes located near the lungs and combined that with tissue sampling techniques in order to make a definitive diagnosis.
Lymph nodes are filters within the lymphatic system, which carries immune system cells that fight off infections. Cancer cells often break off from tumors, travel through the lymphatic system and collect in the nodes, where they can start forming new tumors. Generally speaking, the degree of this spread, or metastasis, determines the prognosis of the cancer.
For their study, know as a meta-analysis, the Duke researchers combined the data from 18 small clinical trials evaluating the procedure's diagnostic accuracy in detecting the spread of non-small cell lung cancer in 1,201 patients. Non-small cell lung cancer, which represents about 80 percent of all lung cancers, is a fast-growing form of the disease.
The researchers found that the procedure -- known technically as endoscopic ultrasound with fine needle aspiration -- correctly excluded involvement of chest lymph nodes with cancer 83 percent of the time. The procedure also identified 97 percent of the patients whose lymph nodes contained cancer. There were no major complications in any cases, the researchers said.
"The results of our study reflect the safety and accuracy of this procedure for staging of patients with newly diagnosed lung cancer," said Carlos Micames, lead investigator of the study. "This is important information that is required for deciding the most appropriate therapy, and that now can be obtained accurately with relative ease during an outpatient procedure with conscious sedation."
Gress said that wide adoption of the procedure would mean that probably about 30 percent of lung cancer patients would avoid the need for more invasive approaches for staging of their disease. In one of these procedures, surgeons take samples through slits in the chests of patients, who must receive general anesthesia. The endoscopic ultrasound procedure takes about 20 minutes and requires the same mild sedation used during a colonoscopy procedure.
"This study demonstrates the important role for endoscopic ultrasound with fine needle aspiration to stage patients with lung cancer," Gress said. "The procedure is widely available in academic medical centers and has begun to branch out to other community referral centers over the past five years. What has held back the wider use of the procedure is the lack of available training opportunities for gastroenterologists interested in learning this procedure. This is an advanced procedure requiring an additional year of training to become proficient."
The researchers are currently conducting an analysis to evaluate the cost effectiveness of the procedure.
Other members of the team were Douglas McCrory, Darren Pavey and Paul Jowell.