Colorectal cancer usually begins as a small polyp and grows slowly; early stages are often silent. When warning signs appear they typically reflect tumor size, location, and bleeding. Key symptoms include: Persistent change in bowel habitsAlternating constipation and diarrhea, narrower pencil-shaped stools, or sudden urgency that lasts more than a few weeks. Blood in or on the stoolBright-red coating, dark maroon mixed blood, or occult bleeding detected only by testing; hemorrhoidal bleeding is usually fleeting and separate. Abdominal discomfortCramping, gas pain, bloating, or a feeling of incomplete evacuation; right-sided tumors may cause vague aching while left-sided lesions classically provoke colicky... Learn more