Renowned radiologist tells development of nonvascular stents
Song Ho-young
Professor in Department of Radiology, University of Ulsan College of Medicine
Song Ho-young is a renowned radiologist and a developer of nonvascular stents that can be used to treat strictures in many areas of the body. Throughout his career of more than 30 years, he has received prestigious awards in Korea and overseas, including the country’s highest award for science and engineering from the government (2008).
One of the hardest things for radiologist Song Ho-young was seeing patients suffer from an esophageal stricture, a narrowing of the tube that runs from the throat to the stomach. Many of them suffer the condition as a complication of inoperable esophageal cancer, which made it difficult for them to swallow food. Thirty years ago, there was almost nothing Song could do for them. One day, however, he came up with the idea of placing a Celestin tube in the patients’ narrowed esophagus to alleviate their suffering. But developing the procedure proved to be challenging; the normal esophagus was only 2 centimeters in diameter, and it was difficult to fix the exact problematic area of the tube. “But that was the only thing I could do for them,” Song said in an interview. “Then I came across articles about endovascular stents in an international journal. I immediately flew to the M.D. Anderson Cancer Center in Texas to meet the author, Dr. Kenneth C. Wright.” After learning the mechanism of the stent, which allows passage through strictures within the body, Song returned to Korea and set up a machinery lab at Chonbuk National University Hospital, where he worked as a professor. Few — even himself — expected the lab would become the birthplace of some of the most successful nonvascular stents at the time. “Thanks to the kind Dr. Wright, I developed stents using silicone and later using stainless steel, but it turned out to be just the beginning of a long struggle,” he said. Because the hospital, just like many others in the country in the 1980s, did not have proper facilities for animal testing, so Song raised dogs on his own and conducted experiments on them on weekends. He also visited hardware stores to develop a stent delivery system from scratch.
Yet his efforts were not appreciated much at the hospital. Many raised eyebrows to what they believed was “not a job of doctors” at that time. “The atmosphere is very different today as the government pushes hospitals to invest more in research, but almost no one knew its value back then,” Song said. Finally, after years of struggle, in 1991, he conducted the world’s first metal stent placement in the human esophagus. “Of the eight esophageal cancer patients who received the procedure, no one had problems such as esophageal rupture or stent migration,” he said. After moving to Asan Medical Center in 1993, Song kicked his efforts to make the stent self-expandable, replaceable, smaller and more flexible into high gear. To make his work more efficient, he founded S&G Biotech in 2000, separating the tasks of research and development and delegating them to their respective groups of experts. Although he developed the nonvascular stents to help esophageal cancer patients, they are now also used to treat strictures in many other areas of the body, including the urethra, gastrointestinal tract, respiratory tract, biliary tract, duodenum and colon. For example, an obstructed tear outflow tract, which could cause epiphora, a condition that involves the inadequate drainage of tears, can now be treated with the stents. During his 30-year career, Song has received many prestigious awards in Korea and abroad, including the nation’s highest award for science and engineering from the government in 2008, the International Cooperation Award from the Chinese Interventional Radiological Society in 2010 and the Gold Medal Award from the Society of Interventional Radiology in 2016. He also founded the Society of Gastrointestinal Intervention to share his know-how with scholars across the world. Meanwhile, he has also published more than 380 papers in medical journals and received 26 patents for stent technologies.
The future of stents
The key to treating narrowed tracts is to keep the stent in them for about six months, which is deemed enough time for them to recover. This long recovery period, however, poses complications, Song said. “For example, roughly 70 percent of non-cancer patients with a narrow esophagus show complications in the first two months and need to get their stent replaced until their esophagus becomes properly functional,” he said. “The current stents are not effective and safe enough for everyone.” Tissue growth is one of the most common complications. The drug-eluting stent, which slowly releases a drug to block cell proliferation, was developed to resolve the issue but failed to do so. But Song believes that bioresorbable stents, which are still being developed, will resolve the issue eventually. These stents, many of which are made of polylactic acid, a naturally dissolvable material, are known to have fewer side effects. “I’m pinning my hopes on my students, whom I believe can and will develop stents with almost no side effects,” he said. “One of my plans before my retirement is to improve the research system at the hospital to help them do so.” Thanks to Song, who has advised Korean companies in developing nonvascular stents, the nation’s nonvascular stent exports in 2012 was 6.4 billion won ($5.7 million), larger than its nonvascular stent imports (3.4 billion won), according to the Korean Health Industry Development Institute’s latest data. This feat is impressive, given that Korea imports the most vascular stents. According to the Korea Institute of Science Technology, the global stent market is valued at around 10 trillion won and is expected to grow fast.
‘Global medical power is moving to the East’
During his sabbatical from 2004 to 2005, Song looked at whether China had the potential to be a medical powerhouse. “I saw the tremendous potential the country had during the year, and I became reassured of its bright future during my second sabbatical from 2013 to 2014,” he said. “I believe the global medical power is moving to the East, which also means a big opportunity for Korea.” During his six-month stay in Nanjing, Song also traveled to many other parts of the country to lecture doctors at hospitals about stent development and writing English-language papers for journals. “Every time I meet young doctors, I encourage them to learn Chinese as well as English, as these language skills will open enormous opportunities for them,” he said. Song started to learn Chinese 16 years ago to better communicate with his Chinese students. Today, he is fluent enough to lecture in Chinese. He believes educating Chinese doctors is important because they can help their country play a larger role in saving and improving people’s lives at home and abroad. After his retirement, which is three years from now, Song plans to travel the world and settle down in China to continue educating Chinese doctors. “I have had mentors who greatly helped me grow into a better doctor,” he said. “Now, it’s my turn to do the same.”