Signs of colorectal cancer

Photo of a woman with abdominal pain
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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 , but they are usually caused by another, non-cancerous condition.

Possible signs of 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), 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.

Adelstein BA, Macaskill P, Chan SF, Katelaris PH, Irwig L. Most bowel cancer symptoms do not indicate colorectal cancer and polyps: a systematic review. BMC Gastroenterol 2011; 11:65.

Jellema P, van der Windt DA, Bruinvels DJ, Mallen CD, van Weyenberg SJ, Mulder CJ et al. Value of symptoms and additional diagnostic tests for colorectal cancer in primary care: systematic review and meta-analysis. BMJ 2010; 340: c1269.

IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. informedhealth.org can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

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Updated on January 26, 2017
Next planned update: 2020

Authors/Publishers:

Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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