Symptoms of colon and rectal cancer

The cancer presents because it either bleeds or it causes disruption of the normal bowel function or because it has spread beyond the bowel and it is the secondaries (metastases) causing symptoms.

 

Clearly, for the first two, it depends on where in the bowel the tumour has arisen.

 

In the rectum a cancer that bleeds is easily and early detected (so long as the fresh red blood is not dismissed as bleeding haemorrhoids), whereas when a caecal cancer bleeds (the caecum being at the other extreme of the large bowel) then the blood will be largely digested by the time it is excreted and not noticed; such caecal cancers usually present with anaemia.

 

A change in bowel habit: frequency, texture of stools, discomfort on defaecation etc may be noticed by the patient and is the next most important presenting feature. Vague abdominal pains, bloating or weight loss are symptoms which are not very helpful to the clinician but not infrequently present.

 

More advanced tumours may present with bowel obstruction or even bowel perforation or with weight loss and general decline in health if the tumour has metastasised (spread further afield e.g. the liver).