A patient with CRC often has symptoms only when the cancer is advanced and these symptoms can be varied.  The following are the common symptoms:

1. Change in bowel habits.  A colon cancer can cause partial obstruction of the colon leading to “holdup’ of faeces and a delay in passing motion.  It can also irritate the colon resulting in frequent loose stools.  In short, a person with a change in bowel habits of more than 6 to 8 weeks should consult a doctor.
   
   
2. Rectal bleeding.  A rectal cancer can present with fairly fresh bleeding separate from faeces due to its proximity to the anus.  It can be mistaken for bleeding from piles.  Bleeding from colon cancer is usually darker and mixed with the stools.  Rectal bleeding is a serious symptom and must be investigated especially in individuals above 40 years old.
   
   
3. Abdominal distension and discomfort.  This is a vague symptom which can also be due to other abdominal problems e.g. irritable bowel syndrome, gallstones.
   
   
4. Difficulty or pain during defaecation.  This applies to rectal cancer which obstructs the passage of faeces and considerable force is needed to pass motion.  There is also a painful sensation of incomplete emptying called tenesmus due to the presence of a tumour in the rectum.
   
   
5. Presence of anaemia and weight loss.  Anemia is often associated with a right sided colon tumour which has bled unnoticed for a long time (occult bleeding).  Anaemia may result in giddiness, weakness & fainting spells.  Significant unexplained weight loss can be often due to a serious illness e.g. cancer.
   
   
6. Presence of an abdominal mass.  A right sided colon cancer can present with an abdominal mass which is uncomfortable and detected by the patient.
   
   
7. Colorectal cancer can present acutely as an emergency in two situations:
   
   
   1. Bowel perforation.  An advanced CRC can erode through the colon wall and cause a perforation with leakage of faeces causing peritonitis and septicaemia.
      
      
   2. Bowel obstruction.  Left sided colon cancer often grows around the colon and cause total obstruction.  The patient complains of constipation, abdominal distension and vomiting over a period of few days.  An emergency operation is required.
   
   Both acute presentations are associated with poor survival even after treatment of the CRC.