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Colorectal cancer

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Signs and symptoms of colorectal cancer

A sign is something that can be observed and recognized by a doctor or healthcare professional (for example, a rash). A symptom is something that only the person experiencing it can feel and know (for example, pain or tiredness).

Colorectal cancer may not cause any signs or symptoms in its early stages because there is lots of room in the abdomen where a tumour can grow. Symptoms often appear once the tumour blocks (obstructs) or causes ulcerations (sores) in the colon or rectum.

The signs and symptoms of colorectal cancer can also be caused by other health conditions. It is important to have any unusual symptoms checked by a doctor.

Signs and symptoms of colorectal cancer are:

  • change in bowel habits
    • narrowing of stools (due to partial blockage of the large intestine)
    • red, bloody bowel movements
    • black, tarry bowel movements (melena)
    • mucus in the stool
    • persistent diarrhea
    • persistent constipation
    • rectal bleeding between bowel movements
    • feeling that the bowel has not completely emptied
    • urgent need to have a bowel movement
  • abdominal discomfort
    • pain
    • cramps
    • gas
    • bloating
    • fullness
    • a lump may be felt in the abdomen
  • changes to digestion
    • nausea
    • vomiting
    • loss of appetite
  • fatigue
  • weight loss
  • anemiaanemiaA reduction in the number of healthy red blood cells.
    • usually a result of bleeding from within the bowel
    • causes fatigue, shortness of breath and weakness
  • bowel obstruction (blockage)
  • perforation (piercing) of the bowel (large intestine) accompanied by fever and pain
  • weakness
  • frequent urinary tract infection (as a result of fistulafistulaAn abnormal opening or passage between 2 internal organs or between an internal organ and the surface of the body. formation or perforation into the bladder)

Colorectal cancer symptoms depend on where the tumour is located in the colon or if it is in the rectum. Blockage of the ascending (right-side) colon is unlikely because the stool in this part of the colon is still in liquid form and can pass a partial blockage or constriction quite easily.

  • Black, tarry bowel movements, called melena, are usually associated with tumours of the ascending colon.
  • Bright red rectal bleeding either mixed with or coating the surface of the stool is most common with tumours of the descending (left-side) colon or rectum.

Late signs and symptoms

Late signs and symptoms occur as the cancer grows larger or spreads to other parts of the body, including other organs. Not all people who have advanced colorectal cancer will have the following late signs and symptoms:

  • severe abdominal pain
  • buildup of fluid in the abdomen (ascites)
  • enlargement of the liver (hepatomegaly)
  • jaundice
  • enlarged lymph nodes
  • pain in the hip or buttock
  • breathing problems
  • loss of appetite


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