Mayo Magazine

2 Doctors + 2 Instruments
Equal Effort Improves Lung Cancer Staging

Jorge Pascual, M.D., and Michael Wallace, M.D.

EUS endoscopic ultrasound Scope is placed into the esophagus to view back of the lung

EBUS endobronchial ultrasound Scope is placed into the airway (bronchial) to view the front and sides of the lung

A simple maxim helps define the Mayo Clinic Model of Care: Two (sometimes more) heads are better than one for treating patients. At Mayo Clinic Florida, researchers have coupled this philosophy with advanced technologies to discover that two high-tech endoscopes are better than one round of surgery, the traditional approach, to diagnose the spread of lung cancer. In fact, the combination of the two scopes is almost perfect, according to recently published research.

The point system
Staging, a four-point scoring system that physicians use to determine the extent to which cancer has spread, is the most important variable in treatment decisions and prognosis for lung cancer. Physicians assign scores based on tissue samples taken from masses in the lung and surrounding lymph nodes. Patients with stages 1 or 2 are generally treated with surgery. The majority of stage 3 and stage 4 patients are treated with chemotherapy and/or radiation.

Determining a cancer's stage is vital to providing the right treatment; however, accurate lung cancer staging has been difficult until recently.

Two instruments, better results
Led by Michael Wallace, M.D., a gastroenterologist, the Florida team has developed a combined technique that uses two types of endoscopes to stage lung cancers. The procedure takes about two hours, requires only a mild sedative and patients go home the same day. Even better, it's highly accurate and, to date, complication-free, Dr. Wallace says.

"We've used this technique on more than 150 patients; it's accurate 97 percent of the time, and so far we've seen no complications," Dr. Wallace says.

Prior to using the combined technique, the best way to stage lung cancer tumors was surgical biopsy of lymph nodes in the chest — the first place lung cancer tumors spread after they leave the lungs. But trying to stage lung cancer by surgical means is accurate only about 50 percent of the time. Also, the procedure requires general anesthesia and can sometimes result in an overnight hospital stay.

Collaborating for a clearer view
Prior to joining Mayo Clinic in 2002, Dr. Wallace conducted extensive research at the University of South Carolina on endoscopic ultrasound (EUS), a flexible tube with an ultrasound probe and a very thin needle.

Through their experiences, Dr. Wallace and colleagues noted that the newer equipment allowed them to clearly see the lymph nodes behind the lungs, which sparked an idea: perhaps the technology could be used for lung cancer staging.

The chance to better explore that possibility lured him to Mayo Clinic, Dr. Wallace says. Because of Mayo's reputation for collaboration, he would have the opportunity to work with lung specialists and surgeons to determine if the equipment would help improve lung cancer staging.

"The biggest barrier to this type of research is the fact that most institutions don't encourage collaboration among physicians," Dr. Wallace says.

Shortly after his arrival, Dr. Wallace had the opportunity to put Mayo's collaborative environment to use. Olympus Corporation asked him if Mayo would consider testing a new type of ultrasound probe, called an endobronchial ultrasound probe (EBUS). Essentially a smaller version of the EUS probe, it was designed for pulmonologists, who use the probe to explore the lungs.

As they tested the equipment, Dr. Wallace and Jorge Pascual, M.D., a pulmonologist at Mayo Clinic Florida, realized that EBUS provided excellent views of the lymph nodes in front and on either side of the lung. From there a match was made, Dr. Pascual says.

"With the EUS, we knew we could see behind the lung, but with the EBUS we could see the sides and front, so the two scopes together would give us the ability to see everything we needed to see to accurately determine the stage of lung cancer," he says.

Study benefits patients
Funding from the National Cancer Institute and Olympus enabled Drs. Wallace and Pascual, as well as cardiothoracic surgeon John Odell, M.D., to begin a large research study to evaluate the effectiveness of lung cancer staging techniques. They looked at EBUS, EBUS plus EUS, and surgical biopsy. Their study is the only one in the United States to compare these techniques, and it is the largest study of its kind in the world.

Together, EBUS and EUS proved more accurate than surgery, and the combination of the two devices was 97 percent accurate in determining the stage of lung cancer. In creating a test with such a high degree of accuracy, the team is saving patients from unnecessary surgeries, says Dr. Odell.

"This helps us avoid a scenario where we find out on the operating table that a patient has a tumor that has spread beyond the lung," Dr. Odell says. "These patients don't benefit from surgery, in terms of producing a cure for the disease, and yet they're still exposed to all the risks and complications that go along with surgery."

Passing on knowledge
At Mayo Clinic Florida, the combination of EBUS and EUS has become the standard technique for staging lung cancer. Drs. Pascual and Wallace say their immediate focus is to educate other physicians on the technique. They have begun training their Mayo colleagues, and they're also receiving requests from physicians at other institutions to observe the technique.

The Mayo team also wants to perform additional research to expand the use of the equipment. One scenario they want to investigate is its use for re-staging of lung cancer. Patients have computed tomography (CT) scans to assess their response to chemotherapy or radiation therapy for the disease, but these scans offer only limited views of the lungs, Dr. Wallace says. EBUS and EUS could be used to determine if the cancer was still outside the lungs and could indicate to physicians how well the patient was responding to therapy.

"This experience really exemplifies what Mayo is all about," says Dr. Pascual. "It is combining everything we do — patient care, education and research — and it increases the quality of patient care."