Can somebody please tell me if a symptom of bowel cancer/colon cancer is diarrhea? 

All I keep seeing is 'a change in bowel habits'. Can anybody here tell me if they experienced uncontrollable and ongoing diarrhea with their bowel cancel before or after diagnosis.

Please don't respond with 'could be IBS' etc. I'm specifically asking about bowel cancer.

I always thought a tumour causes constipation due to blocking the bowel but if anybody can confirm otherwise I will be very grateful.

Person concerned also has a constant dull ache in stomach that never goes away and is booked for a CT scan in the next few weeks.

Thanks a bunch