Signs & Symptoms of Rectal Cancer

The symptoms and signs of rectal cancer can be dependent on many factors and in some cases rectal cancer may be present without any symptoms at all.  This further elucidates the urgent need for increased screening of potentially at-risk individuals.  More info on whether or not someone is ‘at-risk’ can be found in our risk factors explained page.

The signs you should be most aware of include the following:

Blood in Stool.jpg


  • This is the most common symptom and is present in about 80% of individuals diagnosed with rectal cancer.  While other medical issues such as hemorrhoids can cause rectal bleeding, it is recommended that you seek medical care as soon as possible if you experience any rectal bleeding, particularly if for any extended period of time.
  • Prolonged bleeding may lead to anemia or cause feelings of fatigue, shortness of breath or light headedness


Change in Bowel Habits

·The key here is the ‘change’ – if the consistency, size, or frequency of your bowel movements have changed and it is not clearly explained by a modification in diet or other circumstance, this can also be a very important symptom to watch out for. 

  • Thin, Loose or Fibrous stools - In many cases, due to the presence of the tumor, rectal cancer can cause very thin, loose or fibrous stools.
  • Bowel obstruction – rectal tumors can grow large enough to prevent normal passage of stool.  This can cause severe constipation, abdominal pain or cramping.  It is this obstruction or near-obstruction that often causes the very thin stools that can occur in more locally-advanced rectal tumors.
  • Incomplete bowel movements – it is common that an individual with rectal cancer may have sensations of incomplete emptying or evacuation of stool.


Weight loss

While it does not always occur, cancer of any type may cause unexplained weight loss.  Any unexplained weight loss which is in the absence of a diet or exercise program should warrant medical attention.


Pain, Discomfort

Potentially resulting from tumor size and possible obstruction, rectal cancer can cause extensive abdominal pain, cramping or bloating.  If you experience these symptoms in conjunction with any of the above issues like bleeding or changes in bowel movements, please seek medical attention.