Endoscopic Mucosal Resection (EMR) for Early-Stage Gastric Neuroendocrine Tumors

Endoscopic mucosal resection (EMR) is a type of minimally-invasive endoscopic procedure used to remove early-stage gastric neuroendocrine tumors (NETs), which originate from neuroendocrine cells in the stomach wall. These cells produce hormones controlling the release of gastric juices and how quickly food moves through the stomach.

EMR typically involves the insertion of a thin, tube-like instrument called an endoscope down the esophagus and into the stomach. Operative tools passed through the tube are then used to remove the tumor.

There are several techniques through which EMR is performed, which includes traditional or conventional EMR and modified EMR procedures such as anchored, cap band and under-water EMR.

Traditional EMR

This technique involves the injection of a solution, such as glycerol or saline solution, into the submucosa to lift the lesion and separate it from the healthy tissue underneath. Once the lesion is lifted, a pre-looped snare is moved through the endoscope and looped around the base or parts of the lesion, depending on its size. A hot or cold snare is used to remove the tumor itself. Hot snare involves an electrical current being passed through the wire loop, which seals the wound as the lesion is separated and removed. This is known as electrocautery. For cold snare, the snare simply tightens at the base or parts of the lesion and cuts the tumor off without the use of any electrical current.

Anchored EMR

Anchored EMR works similarly to traditional EMR. After lifting the submucosa, the snare tip is placed on the healthy tissue around the lesion and a small slit or incision is made using an electrical current. Subsequently, the snare tip is put into the incision and anchored into the tissue. As such, the remaining part of the snare can open around the lesion more securely. This better ensures the removal of the tumor in its entirety, with a sufficient margin of healthy tissue (known as an en bloc resection).

Cap band EMR

This technique is typically used for lesions in the gastric cardia. First, the lesion is aspirated or suctioned into a transparent cap at the tip of the endoscope. Afterward, an elastic band is secured around the lesion's base, with the lesion being removed using an appropriate snare closed below the band.

Under-water EMR

This technique is similar to traditional and anchored EMR, However, instead of a solution like glycerol or saline, under-water EMR uses water to lift the lesion, as the submucosal lumen is filled with H₂O.

EMR is usually performed by a gastroenterologist, and under conscious sedation. This means you will be administered sedatives through your vein (intravenous) to keep you relaxed and sleepy but not unconscious. You will still be able to hear what your doctors or nurses are saying to you and carry out simple instructions. While you may feel slight movement or pressure, you shouldn’t feel any pain and you might not be fully aware of what goes on during the procedure. You may also be given anesthetic spray beforehand to numb your throat. This makes it easier for the endoscope to pass through your throat and into the esophagus.

Overall, EMR procedures have been shown to be safe, cost-effective, and minimally-invasive. However, do take note that a limitation of EMR is that its success depends on the size of the lesion. This means that the chances of achieving a complete resection are higher with smaller lesions. On the other hand, it may be more difficult to remove larger or deeper lesions in one piece with EMR. For such tumors, hybrid techniques involving endoscopic submucosal dissection (ESD) may need to be considered.