Can Blood Tests Detect Early-Stage Gastric Cancer?

During the early stages of gastric cancer, blood test results are often normal and typically show no significant abnormalities. This is because early gastric cancer often lacks noticeable symptoms and rarely causes gastrointestinal bleeding. As a result, common indicators in blood tests—such as signs of anemia or elevated white blood cell counts due to internal bleeding—usually remain within normal ranges. Therefore, routine blood tests are not reliable for detecting early-stage gastric cancer.

More effective methods for diagnosing early gastric cancer include endoscopic examinations and identifying elevated tumor markers. These markers may include relatively new indicators like increased levels of pepsinogen and gastrin-17, as well as the presence of Helicobacter pylori infection, which can collectively suggest the possibility of early gastric cancer.

In clinical practice, early gastric cancer is often discovered incidentally during endoscopy performed for unrelated symptoms or other gastrointestinal concerns. This is because gastric cancer is often a "silent" tumor in its early stages, meaning it grows superficially and only affects the mucosal or submucosal layers without causing noticeable symptoms. In some cases, patients may seek medical attention due to conditions like gastritis or peptic ulcer disease, and gastric cancer is identified during investigation—though not necessarily linked to their initial symptoms.