Early Stage Stomach Cancer Always Causes Black Stools

Many people believe that black stools are a definitive sign of early stage stomach cancer. However, this is not always the case. The color of the stool in the early stages of gastric cancer depends on whether there is gastrointestinal bleeding and the amount of blood present.

Black stools, also known as melena, typically indicate upper gastrointestinal bleeding. This refers to bleeding that occurs in the upper digestive tract, specifically above the horizontal part of the duodenum. As the blood passes through the lower digestive system, bacteria in the intestines metabolize the iron in red blood cells, causing the stool to turn black.

The color of the stool is also influenced by the volume of bleeding. If the amount of blood loss is less than 5 mL, it may only be detectable through a fecal occult blood test and may not visibly darken the stool. It's only when the bleeding reaches a certain volume—usually more than 50 mL—that the stool becomes noticeably black.

In more severe cases, when blood loss exceeds 250 mL, symptoms may include vomiting, hematemesis (vomiting of blood), or the expulsion of coffee-ground-like material. It's important to note that black stools are not exclusive to stomach cancer. Other conditions such as gastric ulcers, duodenal ulcers, biliary tract bleeding, and duodenal tumors can also cause melena.

Therefore, individuals experiencing black stools should seek medical attention promptly. Diagnostic procedures such as gastroscopy, duodenoscopy, or small intestine endoscopy are essential for identifying the underlying cause. Early detection and diagnosis are crucial for effective treatment and better health outcomes.