Earlier this year, Naohisa Yahagi, MD, PhD, joined Stanford Department of Medicine after decades of advancing a less invasive way to treat early cancers of the digestive tract.
Yahagi came to Stanford from Keio University School of Medicine in Tokyo, where he served as a professor of medicine and led research and development in minimally invasive treatment at the university's cancer center. He has also held major leadership roles in the field, including serving as president of the Japanese Gastrointestinal Endoscopy Society's annual congress.
At the center of his career is a procedure called endoscopic submucosal dissection, or ESD. The technique allows doctors to remove some early-stage tumors from the stomach, esophagus, and colon through an endoscope — a flexible tube passed through the mouth or rectum — potentially allowing appropriately selected patients to avoid open or laparoscopic surgery and, in many cases, leave the hospital as soon as the following day.
Yahagi was among the pioneers who helped develop and advance ESD. He developed specialized cutting tools, including the flex knife and dual knife, that are now widely used by endoscopists around the world. He also developed techniques that use pressurized fluid to help separate the tumor from the surrounding tissue, making it easier to remove, as well as methods for closing the wound afterward.
His work has helped turn ESD from a highly specialized procedure used mainly in Japan into an approach increasingly available to patients in other parts of the world. He has also trained many of the physicians who now perform and teach the technique.
Finding a Better Way to Remove Early Tumors
"More than 25 years ago, doctors could remove only relatively small growths through an endoscope," Yahagi explains. "They typically used a wire loop, called a snare, to capture and cut away the tissue. But the wire could slip, making it difficult to remove larger or flatter growths completely."
Yahagi began exploring whether doctors could first cut around a growth and then carefully separate it from the tissue underneath. The tools available at the time, however, were difficult to control and could cause serious bleeding or create a hole in the digestive tract.
His breakthrough came when he began using the small tip of a thin wire to make more controlled cuts. That idea led to the development of the flex knife and, later, the dual knife. Yahagi eventually found that he could carefully cut beneath the entire growth and remove it in one piece, allowing for more accurate pathological assessment and prevention of local recurrence.
This work contributed to the development of what is now known as ESD.
The procedure was controversial at first. Some surgeons and gastroenterologists considered it too risky, and early complications led some hospitals to temporarily stop using it. Yahagi continued refining the technique, developing safer tools and helping build evidence that it could work.
Over time, ESD became a standard treatment for appropriately selected early digestive tract cancers in Japan.
Building the Field at Stanford
ESD is now widely used in Japan and other parts of Asia and has gained ground in Europe. Adoption in the United States has been slower, in part because relatively few physicians have received extensive training in the procedure and insurance reimbursement remains limited.
Yahagi believes Stanford is well positioned to help change that. "California has a large and diverse patient population, including people at increased risk for stomach cancer," he says. "Stanford's location in Silicon Valley also offers opportunities to work with engineers and companies developing new medical devices."
At Stanford, Yahagi plans to create a step-by-step training program for endoscopists. Physicians would begin with computer simulations, move on to physical models and animal training, and eventually perform procedures with close clinical supervision.
He also hopes to reduce the number of patients who undergo colorectal surgery for lesions that could instead be managed by advanced endoscopic treatment. This includes lesions with uncertain pathology as well as benign lesions that are referred for surgery because advanced endoscopic resection is not readily available.
Yahagi has set a goal of substantially reducing the number of avoidable colorectal surgeries in the United States over the next five years.
Achieving that goal will require close collaboration among gastroenterologists, surgeons, pathologists, and other specialists.
"I'm not sure if it is possible," he said. "But by working together with colleagues across the United States, I believe we can make it possible."
