Nine years after Saowanee Ngamruengphong, M.D., brought a minimally invasive stomach-saving procedure to Johns Hopkins, she is using it to treat more patients than ever, and is training others in the technique of endoscopic submucosal dissection (ESD).

Invented in Japan in 1995, ESD is still fairly unusual in the United States.

Ngamruengphong, a therapeutic endoscopist, learned the painstaking process in 2016, when she traveled to Japan to study advanced therapeutic endoscopy techniques at Tokyo’s National Cancer Center, the world’s foremost facility for innovative endoscopic removal of gastric cancers.

During ESD, a special needle knife tool is passed through an endoscope to carefully remove lesions in the gastrointestinal tract by slowly and methodically separating the lesions from the muscle wall of the gastrointestinal tract — such as in the esophagus, stomach or colorectum — without damaging or cutting through muscle tissue.

The endoscope’s electrocautery knife makes it possible to cut carefully, a tiny bit at a time, around the outside of the lesion, making ESD particularly suitable for cases in which the tumor or lesion attaches to the layer between the lining of internal organs and the muscle wall.

ESD techniques and tools have improved in recent years, says Ngamruengphong. The knife is now more developed so that she can use it to inject a solution between the wall of the stomach and the lesion, creating more space to maneuver.

Even the injection solution is better, she says — it is now formulated to hold the lift longer. Also new is traction assisted saline immersion, which is techniques that involve performing the procedure under saline.

“It allows the tissue to float up and separate from the wall,” Ngamruengphong says. “And it gives you magnification because when you put in a scope to see the tissue, the under-saline actually magnifies the image.”

Compared to endoscopic mucosal resection (EMR), which is a simpler and more common technique for removing growths, ESD can be more effective in selected cases, especially for lesions without clear borders and those too large to remove in one piece by other methods. 

ESD usually takes a couple of hours to perform, compared to about 30 to 45 minutes for EMR, but the endoscopist can remove the tumor whole, making pathologic assessment more accurate for cancer margins. Also, Ngamruengphong notes, the patient has a higher chance of cure, and surgery, chemotherapy or radiation are not needed.

Removing the tumor whole, she explains, “is much better for pathologists. They get the whole specimen — and the margins — in one sample. That makes it easier to determine whether we got everything we needed to get.”

Though ESD has become slightly easier with the introduction of new tools and techniques, it is still a difficult procedure.

As vice chair of the American Society for Gastrointestinal Endoscopy’s ESD special interest group, Ngamruengphong trains physicians in ESD and promotes education about it.

She now performs about 100 ESDs each year, Ngamruengphong says, up from 60 or so in 2020.

“It’s still not widely available, compared to other techniques,” she says. “It takes longer and it’s more difficult to do, but sometimes, it’s the only way we can get the tumor out.”

To refer a patient, call 410-933-7495, or reach Ngamruengphong in her office at 410-550-1277.