What does your poop look like if you have colorectal cancer? New onset of bright red blood in the stool always deserves an evaluation. Blood in the stool may be less evident, and is sometimes invisible, or causes a black or tarry stool.
Changes in stool or bowel movement may be suggestive of colon cancer—particularly if you have risk factors for the disease —but there are numerous other explanations for these symptoms. These conditions are far more common but can mimic many of the signs and symptoms of colon cancer.
At diagnosis, 75% of colorectal cancer patients present with bowel habit changes (either diarrhea or constipation). Most people will experience loose stool. Severe watery diarrhea is found in about 17% of patients with colon cancer ( reference ). The color of loose stool is often light brown or yellowish.