The Endoscopic Ultrasound — An Important Tool in Gastric Cancer Diagnosis

Endoscopic ultrasound, or EUS, is an advanced medical tool that combines the principles of endoscopy and ultrasound to give doctors a highly detailed view inside the upper digestive tract. Much like a standard endoscopy, which uses a flexible tube with a camera to examine the esophagus, stomach, and small intestine, the EUS device includes an ultrasound probe at its tip.

This added ultrasound allows doctors to perform scans from inside these organs, producing high-resolution images that reveal much more than a regular endoscopy.

EUS works similarly to how a traditional ultrasound scan is used externally — like on the abdomen or neck — where a probe is placed on the skin to send sound waves into the body, creating images of organs, muscles, and tissues. However, since the stomach and intestines contain air, regular ultrasound from outside the body can’t clearly visualize these structures. EUS overcomes this limitation by placing the ultrasound probe directly inside the digestive tract, bypassing the air to create sharp images of the layers within the esophagus, stomach, and duodenum.

“As part of your workup for suspected gastric cancer, you might go through a variety of imaging studies as well as procedures. Some of these procedures can include endoscopy where a camera is inserted into the mouth and visualizes the lining of the stomach,” Dr. Nicholas Hornstein, a Medical Oncologist at Northwell Cancer Institute in Manhattan, tells SurvivorNet. “This can then be enjoined by an endoscopic ultrasound where they use a ultrasound probe in the stomach to look at the lymph nodes around the stomach, as well as how deeply the tumor may penetrate into the stomach.”

This approach has proven to be a game-changer, especially for diagnosing and staging cancers within the digestive tract. By closely examining the stomach wall layers, doctors can better assess the extent of a tumor and determine the most effective treatment approach. EUS is also valuable for evaluating other conditions, like cysts, tumors in surrounding organs, and pancreatic diseases, providing a powerful way to look deeper into the body’s structures from the inside.

Why is EU Important in Gastric Cancer?

The stomach wall is made up of distinct layers, each with its unique structure and function. These layers, starting from the inside out, are called the mucosa (the innermost layer), submucosa (connective tissue), muscularis (muscle layer), and serosa (the outermost layer). For oncologists and surgeons, knowing exactly which layers are affected by a tumor is essential because it helps determine the cancer’s stage and plan effective treatment.

Standard tests like upper endoscopy or CT scans can’t always provide precise information about which layers the tumor has invaded. That’s where more advanced tools, like endoscopic ultrasound (EUS), come into play, allowing doctors to see the exact layers involved.

Once your treatment team knows which layers are affected, they can classify the tumor using a grading system with the letter “T” followed by a number from 1 to 4. A T1 gastric cancer means the tumor is limited to the mucosa, while a T4 cancer has spread through all layers, reaching the outermost serosa. In simple terms, the more layers the tumor penetrates, the more advanced the cancer is, guiding treatment decisions and helping to predict outcomes.

Additionally, according to the lastest guidelines, EUS is recommended for pretreatment evaluation of all patients with gastric cancer who have no radiographic evidence of metastatic disease (or disease that has spread to distant areas of the body) and have otherwise potentially operable disease.

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