An upper endoscopy, or esophagogastroduodenoscopy (EGD), is a procedure that visually examines the esophagus, stomach, and the first section of the small intestine. A thin, flexible tube with a light and camera, called an endoscope, is passed through the mouth to view the internal linings of these organs. This examination is a primary method for detecting stomach cancer.
The Endoscopic View of a Healthy Stomach
A healthy stomach lining, or mucosa, has a distinct appearance during an endoscopic examination. It is a pinkish-orange or salmon color, with a smooth and glistening surface and prominent, accordion-like folds known as rugae. These folds are a normal part of the stomach’s anatomy that allow it to expand to accommodate food. As the stomach is inflated with air during the endoscopy, these rugal folds flatten, allowing for a detailed inspection of the entire mucosal surface. The tissue appears uniform in color and texture, serving as a baseline to identify potential abnormalities.
Visual Indicators of Early-Stage Stomach Cancer
The signs of early-stage stomach cancer can be subtle, characterized by slight changes in the stomach’s lining. These early lesions may present as localized areas of discoloration, such as pale patches or reddish spots that stand out against the healthy pink mucosa. These color variations can indicate underlying tissue changes not yet visible as a distinct mass.
In addition to color changes, early gastric cancer can alter the surface texture of the stomach lining. An endoscopist may identify areas that are slightly elevated, resembling a small plateau, or slightly depressed and indented. Small, shallow ulcers or growths that resemble polyps may also be signs of early-stage disease.
Advanced imaging technologies, such as narrow-band imaging (NBI), can enhance the visualization of these early cancers. NBI uses specific light wavelengths to highlight the patterns of tiny blood vessels in the mucosa. In early cancer, these vascular patterns often appear irregular and have a clear demarcation line separating the cancerous tissue from the normal surrounding mucosa.
Characteristics of Advanced Stomach Cancer
As stomach cancer progresses, the endoscopic view reveals more pronounced abnormalities. These advanced tumors are classified based on their growth patterns and appearance. One common form is the exophytic or protruding tumor, which grows outward into the stomach cavity and can appear as large, irregularly shaped masses with a cauliflower-like surface.
Another presentation is the ulcerated tumor, characterized by a deep, crater-like lesion. These ulcers have irregular, raised, and firm edges, which distinguishes them from benign peptic ulcers. The base of these cancerous ulcers may be covered with dead tissue or show signs of recent or active bleeding.
A less common but more aggressive form of advanced stomach cancer is infiltrative cancer, also known as linitis plastica. In these cases, the cancer cells spread diffusely throughout the stomach wall, causing it to become thick, rigid, and non-distensible. This gives the stomach a “leather bottle” appearance, as it loses its ability to stretch and contract normally. This form of cancer can be challenging to identify through endoscopy alone, as the surface mucosa may appear relatively normal.
The Role of Biopsy During Endoscopy
While the visual appearance of the stomach lining can provide strong indications of cancer, it is not sufficient for a definitive diagnosis. A biopsy, performed during the endoscopic procedure, is required for confirmation. The endoscope is equipped with channels that allow for the passage of small, tweezer-like instruments called forceps.
Using these forceps, the gastroenterologist can collect multiple small tissue samples from any suspicious-looking areas. Taking several samples from different parts of a lesion increases the accuracy of the diagnosis. These tissue samples are then sent to a pathology laboratory for microscopic examination. A pathologist analyzes the cells to determine if they are cancerous and, if so, to identify the specific type of cancer. This information is needed for planning the course of treatment.
Limitations and Complementary Procedures
A standard endoscopy has limitations. The procedure cannot determine the depth to which a tumor has invaded the stomach wall or whether the cancer has spread to nearby lymph nodes or other organs. This information, known as the cancer’s stage, is needed for determining the prognosis and treatment plan.
To overcome these limitations, other procedures are used in conjunction with endoscopy. Endoscopic ultrasound (EUS) is a specialized procedure that combines endoscopy with ultrasound imaging. An ultrasound probe at the tip of the endoscope provides detailed images of the layers of the stomach wall and adjacent structures, allowing for a more accurate assessment of tumor depth and lymph node involvement. Additionally, computed tomography (CT) scans are frequently employed to detect if the cancer has spread to other parts of the body.