A 60-year-old man with hypertension presented to the hospital owing to fatigue but with no abdominal discomfort, constipation, or diarrhea. Initial investigations revealed that his serum creatinine had risen to 1.54mg/dL (from 1.05mg/dL 4 months earlier). One month later, colonoscopy was performed to screen for colon cancer based on his age, revealing only 3 colorectal polyps located at descending colon (0.5cm), sigmoid colon (1.8cm), and rectum (1.5cm), with no mass. The polypectomy was performed and showed adenocarcinoma with moderate to poorly differentiated cells in the rectal polyp.