Rectal tumors three centimeters in diameter are considered relatively large. Rectal tumors have benign and malignant tumors, no matter which type of tumor, if the diameter reaches three centimeters, it is generally a relatively large tumor. Common benign rectal tumors and rectal polyps, such as its diameter of three centimeters, may be adjacent to the organs caused by extrusion, resulting in the patient to appear in the anxious and heavy (lower abdomen is uncomfortable, very want to relieve stool, after defecation, there is a feeling of defecation), abdominal pain, blood in the stool, stool shape change and other symptoms. Rectal malignant tumors with a diameter of three centimeters can cause intestinal obstruction in addition to the above symptoms, resulting in hyperactive bowel sounds, vomiting, abdominal distension, diarrhea, stopping of defecation, abdominal pain, and weight loss. If the rectal tumor reaches three centimeters, the patient should actively cooperate with the doctor for examination and treatment so as not to delay the condition.