Signs of colorectal cancer

Photo of a woman with abdominal pain (Jupiterimages /

Colorectal (bowel) cancer doesn't cause any symptoms at first and often goes undetected until it has reached a later stage. Certain symptoms may be signs of colorectal cancer, but they are usually caused by another, non-cancerous condition.

Possible signs of colorectal cancer include:

  • Blood in the stool or anal bleeding
  • Anal mucus secretion
  • Change in bowel movements over several weeks (for example constipation or diarrhea, sometimes alternating)
  • The feeling of not being able to empty your bowels properly
  • Pains or cramps in the abdomen (belly) or around the anus
  • Unintentional weight loss
  • Tiredness and physical weakness

All of these symptoms are nonspecific. In other words, they could also be caused by other diseases such as irritable bowel syndrome (IBS), inflammation of the lining of the stomach (gastritis), a peptic ulcer, a food intolerance or an inflammatory bowel disease. Bowel cancer is only rarely the cause, especially in people under the age of 40.