When you have a gastroscopy at a health check-up and hear "early gastric cancer is suspected," your mind usually goes blank. But if you calm down a little and listen to the explanation, it is often a more fortunate situation than it seems. If gastric cancer is found before it has progressed, while it still sits shallowly in the mucosa, the lesion can be removed with the endoscope alone, without opening the abdomen. This is called endoscopic submucosal dissection, or ESD for short.
The principle is simpler than you might think. A fluid is injected beneath the cancerous mass on the inner mucosa of the stomach to lift it slightly, and then a fine electric knife is used to peel away the layer beneath the mucosa, one layer at a time, as if dissecting it. Because it is done by passing the endoscope through the mouth, not a single scar is left on the skin. Unlike surgery that removes the whole stomach, the stomach is preserved intact, so the everyday life of eating and drinking as before is kept almost entirely the same after treatment. That is the biggest advantage.
Of course, not just any gastric cancer can be handled this way. The key is "how early it was caught." It becomes a candidate for the procedure when the cancer is shallow, in the mucosa only, when the size is not too large, and when the risk of spread to the lymph nodes is judged to be low. That is why examining the removed tissue carefully under a microscope is truly important. If the examination turns out that it went deeper than expected, or cancer cells remain at the margins, additional gastrectomy may be needed. Everyone wishes for it to end in one go, but it becomes easier to accept when you take it as a step taken for safety.
The procedure itself usually finishes within an hour or two and is wrapped up with a few days in hospital, but that does not mean there is nothing to be careful about. Because an ulcer is created artificially at the dissected site, complications such as bleeding or perforation (a hole) can rarely follow. So for a while after the procedure you take medication that suppresses stomach acid, and you avoid irritating foods, alcohol, and tobacco to give the wound time to heal. If you see black stools during recovery or your abdomen suddenly hurts severely, do not endure it and inform the hospital right away.
In fact, the very fact that ESD is possible means it was caught that early. Gastric cancer has almost no symptoms in its early stages, so it easily passes by as something like "my stomach feels a bit bloated." Because of that, it is easy to miss the right time for detection. If you are over 40, or have a family history of gastric cancer, chronic atrophic gastritis, or Helicobacter pylori infection, not putting off regular endoscopy is, in the end, the way to protect yourself. Keep in mind, too, that even after removal you must keep up with follow-up endoscopy to watch for recurrence or lesions elsewhere.
What is written here is only a general explanation meant to help you understand ESD. Please be sure to decide the state of your own lesion and the direction of treatment directly in consultation with your care team.