Anti-Reflux "Dua Stent" Benefits Esophageal Cancer Patients

The incidence of cancer arising at the lower end of the esophagus, where it joins the stomach, is rising at a rapid rate. Patients with this type of cancer are often presented with additional difficulties because many are not be able to swallow.

Patients who cannot swallow due to advanced esophageal cancer often have a stent - basically a hollow tube - inserted through the tumor to enable them to drink and eat. The stents must be placed through the tumor with their lower end lying in the stomach. This placement lets food go down but unfortunately it also lets stomach contents reflux, or come back up into the mouth, an unpleasant result that diminishes quality of life and can lead to aspiration or even death. This is of even greater concern when patients are lying flat.

A stent designed by Kulwinder S. Dua, MD, Medical College of Wisconsin Associate Professor of Medicine, allows esophageal cancer patients to eat and also reduces the incidence of reflux. To keep stomach contents where they belong, the "Dua Stent" employs a valve that resembles a windsock.

"Tumors may not cause symptoms for many months because the esophagus can stretch to accommodate and let the food go down," says Dr. Dua. "But when that stretch-ability reserve is lowered, then patients present with the first symptom, which is difficulty in swallowing. Unfortunately, that means that the cancer has been there for many months and sometimes years. Therefore, there is a potential that these patients may not be cured. Not surprisingly, only 20% of them actually survive more than a year once the diagnosis is made."

Improving Quality of Life
"For patient with unresectable esophageal cancer, who cannot swallow their own saliva and have few months to live, major surgery to relieve symptoms can be associated with high rates of mortality or a prolonged hospital stay," notes Dr. Dua. "When we reach that stage, to avoid surgery, we like to use techniques that are done rapidly - even as an outpatient procedure - and are effective with minimal re-interventions. This allows these patients to stay at home and to enjoy the taste of food rather than depending on a feeding tube."

The stents, made of very thin wire mesh, are placed through the tumor using endoscopic and X-ray guidance. When the stent is released it springs open. Stents are effective in relieving difficulty swallowing, and with an attached valve, they have been shown to be also effective in reducing reflux of food from the stomach into the mouth.

"What I did is develop a valve that is attached to the lower end of any of these stents," said Dr. Dua. "This valve is pressure-sensitive. It can withstand a particular amount of pressure, enough to prevent the food from backtracking into the person's mouth, especially when they are sleeping at night and the airways are not protected. But at the same time it's weak enough to buckle in when the person needs to vomit or belch. Then, by drinking a glass of water, the valve can be flipped down again."

Big Inspiration at a Small Airport
Dr. Dua started working on the new stent around 1998. The wire mesh stents on the market were already coated with a thin plastic membrane to keep tumors from getting inside the tube, so he approached a manufacturer and asked if they could simply roll the plastic out a little further to create the valve without having to significantly re-tool the production process. The right thickness and length for the membrane was determined through testing.

"It's like a windsock," said Dr. Dua. "I'm a private pilot, and that's how I got the idea. I was actually, believe it or not, flying into a small airport and I wanted to land and looked at the windsock to see the wind direction.

"At the time I was doing a lot of stenting in patients and used to make them sleep sitting up at night to reduce reflux and gave them strong acid-suppression medications. All these thoughts were passing in my mind and I was wondering about valves and how they could be made without changing the design of the stent…and then, while watching one of these windsocks, I got this idea. We did some dynamic flow studies at the Medical College and determined the pressure gradient that it can withstand."

The US Food and Drug Administration cleared the Dua stent for use in 2002. A British study comparing 25 patients with the traditional "open" stent to 25 who received the Dua stent showed that swallowing improved for both groups. However, 24 of the 25 patients in the traditional stent group experienced reflux, and 19 of those required further treatment. One patient in the traditional stent group died due to aspiration within 24 hours of the procedure.

Only three of the Dua stent patients experienced reflux, and just one needed more treatment. There were no deaths in the Dua stent group.

Dr. Dua stressed that surgery, chemotherapy and radiation therapy are given to patients "when we know that they're going to prolong life and it's worth it. When it is clear that these measures are not going to prolong life, he said, "we use stents that relieve their symptoms and improve the quality of the remaining life."

Dan Ullrich
HealthLink Contributing Writer

MCW Health News presents up-to-date information on patient care and medical research by the physicians of the Medical College of Wisconsin.