(file photo) Retired Navy Capt. Mark Johnston, shown here in 2005 when he was the chief of Gastroenterology at the National Naval Medical Center, examines a patient’s throat to determine if there is damage to the esophagus. Johnston developed a technique of using cryotherapy, typically used for skin cancer, and invented a system to deliver liquid nitrogen to freeze the lining of the esophagus and cure many esophageal diseases.

Retired Navy Capt. Mark Johnston, while still in uniform and serving as Bethesda’s chief of Gastroenterology, invented a device that uses liquid nitrogen to freeze and effectively kill cancerous and pre-cancerous cells in the esophagus — the CryoSpray Ablation System — also known as cryotherapy.

Two studies, ‘‘Endoscopic spray cryotherapy for esophageal cancer: safety and efficacy,” conducted by Dr. Bruce Greenwald, et. al., and ‘‘Safety and efficacy of endoscopic spray cryotherapy for Barrett’s esophagus with high-grade dysplasia,” conducted by Dr. Nicholas Shaheen, et. al., recently lauded cryotherapy for efficacy and safety in a large cohort of patients, including those with cancer.

Johnston, who has been a civilian now for the past five years, thanks the military’s culture for fostering creativity and innovation for his medical invention. He said the Navy offered him the opportunity to ‘‘think outside the box when many doctors were and still are locked-in to a certain way of thinking.”

Ten years ago, Johnston said severe esophageal diseases — like Barrett’s Esophagus, dysplasia and esophageal cancer — had only one treatment. That remedy, known as an esophagectomy, is a procedure to cut out some or all of the patient’s entire esophagus, and re-attach the stomach higher up. The process was painful and forever altered what the patient ate.

Johnston thought about cryotherapy, a technique dermatologists and obstetricians⁄gynecologists commonly use to treat cancerous and pre-cancerous cells.

With an idea, a garage, catheters and other spare parts, Johnston set out to build a crude prototype that earned him a $12,000 grant, which immediately showed the device’s worthiness, but it wasn’t without hurdles.

‘‘We had a problem with the catheters freezing up because of the liquid nitrogen,” said Johnston, who was also director of the Colon Cancer Center at Bethesda, an associate professor of medicine at the Uniformed Services University of the Health Sciences and a gastroenterology consultant to the U.S. Congress, Supreme Court and White House. ‘‘The catheters were 2 mm thick and 4 feet long, so we had to play around with different diameters, pressures, venting and getting a good flow [of the liquid nitrogen spray].”

Little did Johnston know the hurdles to come would be even more challenging. While looking into patent law for his new invention and working with the Department of Defense’s Intellectual Property Office, Johnston was met with the decision to continue researching and forfeit all royalties or stop researching and profit from his invention. When the dust settled, he chose to turn over 100 percent of the royalties to a charitable organization run through his local church.

He also contracted a small company to manufacture the device. He knew just which one to choose, a company that previously donated endoscopes to him free-of-charge for humanitarian work in Albania several years earlier. The company would provide Johnston the much-needed financial backing to continue developing the device and also some engineering support to overcome tougher development dilemmas.

Johnston’s cryotherapy device ultimately received FDA approval — the research was done at the National Naval Medical Center — and has been cleared for use. It is now offered at the Mayo Clinic, Cleveland Clinic, New York University, Cornell University, University of Miami, University of California Los Angeles, Cedars Sinai, Baylor University, University of Texas MD Anderson Cancer Center and Massachusetts General among others.

Cmdr. Brooks Cash, chief of Integrated Gastroentrology Clinic at NNMC, said Bethesda no longer offers cryotherapy, but Walter Reed Army Medical Center (WRAMC) provides it and NNMC beneficiaries are eligible to receive the treatment there, if necessary, through the integrated Gastroenterology Clinic. He said NNMC uses radio frequency ablation therapy, which also kills the cancerous and pre-cancerous cells.

Cash and Army Col. David Horwhat, who performs the cryotherapy procedures at WRAMC, both worked with Johnston in the device’s early development. Cash said the cryo device will be part of the new Walter Reed National Military Medical Center Bethesda. Horwhat said some patients may choose one therapy over another simply because it’s offered at their ‘‘home” facility. That will end, he said, when the joint hospital opens.

‘‘Soon, it’s the same fight — just like the battlefield docs. When we offer radio frequency and cryo, we will be able to treat more patients. They will be in an environment to receive care without personal biases — they can just get the best care possible,” said Horwhat.

Ric Hughen, vice president of sales, marketing and business development of the small company manufacturing the cryo device for Johnston, is also investigating to see if this device can be applicable to other disciplines.

‘‘Lung cancer is the No. 1 cancer in the world, so we’re looking to see if this is applicable to pulmonary [cancer],” Hughen said. ‘‘If cryotherapy can be tolerated in the lungs or other areas of the body, and descent trials prove that, it could magnify 10, 20, 100 fold ... [imagine] how many lives could be saved.”

Cash said other military personnel are working feverishly on research projects right now to keep military medicine at the forefront.

‘‘[Johnston’s device] shows the military’s commitment and priority to research,” Cash said. ‘‘The Armed Forces pushes the envelope and, with the minds we have, the military is poised for more medical innovations and advances in the future and that’s gratifying.”

‘‘I spent 20 wonderful years in the Navy. I had a dream career,” Johnston said. ‘‘It’s a unique environment and [the National Naval Medical Center] is a unique environment ... I think the military has some great men and women, and the environment really afforded me the opportunity to excel in an atmosphere with supervisors who encouraged it.”