Two Ultrasound Procedures Combined Are Superior To Bronchoscopic Biopsy To Detect Lung Cancer Spread
About half of all lung cancers are caught after they have spread to nearby lymph nodes. Biopsy results from these lymph nodes determine the appropriate treatment. Mayo Clinic physicians have shown that combining two minimally invasive ultrasound procedures to biopsy lymph nodes in the chest is superior to standard bronchoscopic-guided biopsy.
Current practice is to surgically open the chest and biopsy suspicious lymph nodes or to use a bronchoscope to guide a minimally invasive needle biopsy. To do this, the patient is sedated, and a doctor advances a bronchoscope into the lungs via the trachea. A small needle at the end collects tissue samples from the region surrounding the lungs, but without image guidance, the samples may or may not be collected from the lymph nodes. "That's not very accurate," says Mayo Clinic gastroenterologist Dr. Michael Wallace. "It's truly hit or miss, but we've been doing it that way for decades," he says.
Over the past six years, Wallace and his colleagues have demonstrated that using endoscopic ultrasound (EUS) to guide needle biopsy of lymph nodes in the chest (mediastinum) is equally if not more accurate than surgical biopsy.
To perform needle biopsy on lymph nodes in the chest using EUS, a physician advances a special endoscope fitted with an ultrasound processor at its tip through the esophagus. This permits the physician to image the surrounding lymph nodes and to guide a small needle through the esophagus into suspicious ones. The limitation of EUS for needle biopsy is that ultrasound does a poor job seeing and sampling lymph nodes in front of the air-filled trachea.
Wallace and his colleagues worked with the Olympus Corporation to design a small ultrasound scope that could pass through the opening of the trachea and into the airways. They thought that by combining EUS with this endobronchial ultrasound scope (EBUS) to see lymph nodes in the front of the chest, they'd get a complete view of all the lymph nodes in the mediastinum.
They conducted a prospective study to compare traditional bronchoscopic biopsy with EUS plus EBUS biopsy. Lung cancer patients in the study were referred for all three outpatient procedures, which were done consecutively and took a total of one hour per patient. A lung specialist performed each bronchoscopic needle biopsy and the EBUS-guided biopsy. Without viewing the procedures or knowing the results, a gastroenterologist immediately performed EUS-guided needle biopsy on the patient. "We rigorously compared the accuracy of the two approaches," Wallace says. "We looked at their individual accuracy and their combined accuracy. We thought combining EUS with EBUS would give us a complete view of the mediastinum. We found that was basically true."
Wallace presented preliminary results from the study July 6 in Barcelona, Spain, at the meeting of the International Association for the Study of Lung Cancer. Bronchoscopic needle biopsy alone only detected a third of lymph nodes that were malignant. EUS alone detected about half of the malignant lymph nodes, and they were all in the back of the chest. EBUS alone detected about two-thirds of the malignant lymph nodes, and they were all in the front of the chest. "By combining EUS and EBUS, we got the detection rate up to 93 percent," Wallace says. "So clearly the two procedures are complementary."
Mayo Clinic has already adopted EUS plus EBUS as the way to perform needle biopsy of mediastinal lymph nodes. The clinic in Jacksonville, a large referral center for EUS, also trains physicians to perform EBUS. Wallace hopes publication of the study results along with continued physician training in EBUS will lead other centers to adopt the combined techniques as standard practice for mediastinal lymph node biopsy.
Mayo Clinic is a multispecialty medical clinic in Jacksonville, Fla. The staff includes 310 physicians working in more than 40 specialties to provide diagnosis, treatment and surgery. Patients who need hospitalization are admitted to nearby St. Luke's Hospital, a 289-bed Mayo facility. Mayo Clinics also are located in Rochester, Minn., and Scottsdale, Ariz. Visit www.MayoClinic.org/news for all the news from Mayo Clinic. - JACKSONVILLE, Fla., July 22, 2005