Dark brown or black stools
If your stool is darker than normal, it usually indicates rectal or colon bleeding. Sometimes it becomes bright red and very noticeable, sometimes the stool becomes darker. This is a major red flag for colon cancer. Of course, there are other causes of blood in the stool, such as hemorrhoids, but if you notice dark or red blood in the stool, see your doctor right away.
elderly with symptoms of colon cancer and abdominal pain