Gastric cancer patients’ blood routine can be normal, but most of them will be abnormal because gastric cancer patients are often combined with gastrointestinal bleeding, which can cause small cell anemia or iron deficiency anemia, and the routine blood test can show a decrease in red blood cell count and hemoglobin, while red blood cell volume and average red blood cell hemoglobin concentration are also decreased. Gastric cancer patients are often combined with chronic atrophic gastritis, which can cause macrocytic anemia or malnutrition anemia due to the lack of endogenous factors, and the routine blood test can show a decrease in red blood cell count and hemoglobin, while the red blood cell volume and average red blood cell hemoglobin concentration are increased.