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.

Colorectal (bowel) cancer doesn't cause any symptoms at first and often goes undetected until it has reached a later stage. Certain problems may be a sign of colorectal cancer, but they are usually caused by something else.

Possible signs of colorectal cancer include:

• Blood in stool (reddish, black or very dark stool)
• Bleeding or secreting mucus (slime) from your bottom
• 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 non-specific. 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, hemorrhoids or an inflammatory bowel disease. Bowel cancer is very rarely the cause of these problems, especially in people under the age of 40.