Doctor uses liquid nitrogen to treat esophageal disorder

//April 13, 2009

Doctor uses liquid nitrogen to treat esophageal disorder

//April 13, 2009

A Lancaster
County doctor has
developed an experimental treatment to help stave off esophageal cancer, and it
all started in his garage.

In the mid-1990s, Dr. Mark Johnston, then a Navy officer,
was working as a fellow in the gastroenterology department at the National
Naval Medical Center
in Bethesda, Md.

Johnston, who hails from a small town in northern New York,
said he developed an idea of how to halt the progression of a condition called
Barrett’s esophagus – which about 220 of his patients had – into cancer.

Often a result of acid reflux, Barrett’s esophagus is
characterized by cells of the esophagus becoming more like those lining the
intestinal tract. The malady puts patients at risk of developing esophageal
cancer, a type increasing at one of the fastest rates in the Western
Hemisphere, Johnston said.

Then, if a patient was judged to be at risk for developing
the cancer, the treatment was surgically removing the esophagus, Johnston said.
Scientists had begun to experiment with forms of ablation – such as heat that
can be used to kill abnormal cells – but the treatments were expensive and
could be painful, Johnston said.

He said he thought employing cryotherapy, like
dermatologists routinely use to remove warts, might work to rid the body of the
abnormal cells.

The grandson of an inventor, Johnston said he constructed
the original piece of equipment in his garage using parts from home-supply

Working with engineer Jennifer Cartledge of Fiber Tech Inc.,
he fashioned a container to hold liquid nitrogen that is connected to a
catheter to spray the substance. That assembly was built into an instrument
called a gastroscope, which is inserted into the throat.

The doctor performing the procedure would spray the liquid
nitrogen into the areas affected by Barrett’s esophagus, thus killing the
abnormal cells.

Johnston soon obtained research grants and began testing the
treatment first in pigs, then in humans. 
The procedure demonstrated promise in both instances.

But patents were very expensive, so Johnston said he went
searching for a corporate partner to bring in investors.

Through his medical mission work with the Christian Medical
& Dental Associations
, he found Fiber Tech Inc., which provided free
equipment for the work.

Through partnership with Johnston, the company eventually
became CSA Medical Inc. Baltimore-based CSA Medical’s sole product is now the
cryotherapy ablation equipment, which the U.S. Food & Drug Administration granted its clearance in 2005.

The Navy granted Johnston intellectual property rights for
his technique but set restrictions on royalties, he said.

If Johnston wanted to continue as principal investigator of
the technique, the Navy ruled he would have to forego all royalties, he said.
Conversely, Johnston said, the Navy told him that if he gave up control of the
project, he could keep the royalties.

“I did some major soul searching and came to the conclusion
this would never go forward without my knowledge and understanding, so I
decided to give up the royalties,” Johnston said.

“To be quite honest, I have been greatly blessed even though
I gave this all away,” he said.

Johnston created the Johnston’s Hope Foundation, a nonprofit
dedicated to aiding Christian medical missions in the Third World, as a result
of the Navy’s decision. CSA Medical sells the systems and gives the foundation
8 percent of the royalties.

To date, 60 medical institutions including the Mayo Clinic and The Cleveland Clinic, use the procedure, which has been performed on more
than 1,000 people, Johnston said.

The risks of using cryotherapy are similar to other types of
ablation, Johnston said, and include bleeding, scarring or pain. But he argued
that cryotherapy is cheaper and less painful than other forms of ablation.

Thirteen papers will be presented at a gastroenterology
conference in Chicago about other doctors’ use of the technique, Johnston said.

Cryotherapy for Barrett’s esophagus is “the new kid in the
block,” said Dr. Richard Sampliner, professor of medicine at the University of
Arizona Health Sciences Center
, Southern Arizona VA Health Care System.

“I think (Johnston’s) done an admirable job of developing a
new technology that represents a modality that could be effective,” Sampliner
said. “It’s just there is a device available now that is quite safe.”

There has been no head-to-head comparison of different
treatments of Barrett’s esophagus, in part because many of the types of
ablation are relatively recent developments, said Dr. Nicholas Shaheen,
associate professor of medicine and epidemiology at the University of North

Of those, he said cryotherapy is the newest.

“Dr. Johnston really has been a innovator, a real pioneer in
these issues,” Shaheen said. “I think (cryotherapy) holds great promise as
potential treatment for esophageal cancer and pre-cancer of the esophagus. The
early data on it are very promising.”

Johnston said other doctors continue to research the uses of
cryospray ablation and that he is exploring the use of cryospray ablation in
treating early-stage esophageal cancer and as a palliative treatment for more
advanced stages of the disease.

In one soon-to-be-published study, cryospray ablation caused
remission in early-stage esophageal cancer for 90 percent of the 80 patients,
Johnston said.

Dr. Bruce Greenwald led another soon-to-be-published study
that found treatment with cryotherapy ablation, in concert with other
techniques, eliminated stage-one esophageal cancer in more than 80 percent of
85 patients.

Greenwald, an associate professor of medicine at the
University of Maryland School of Medicine, said he has been experimenting with
cryotherapy ablation since 2006.

“It looked like it was a really exciting new technique that
gave us capabilities we didn’t have before in treating conditions in the
esophagus,” he said.

At this point, the treatment needs to be tested in a larger
sample size to see how well-tolerated it is in the population at large, he

Johnston is now a partner at East Hempfield Township-based
Lancaster Gastroenterology Inc., having retired from the Navy in 2005 with 20
years of service and the rank of captain.

Johnston found out about Lancaster because he met one of the
practice’s doctors while performing medical mission work in China, he