What are the symptoms of colon problems?

Agree. I would just add that all of the above can be caused by other diagnoses than colon cancer. But i agree if any of the above are present please get evaluated by a specialist.
Change in stool. When problems arise in the colon (the large bowel) it usually affects the bowel movements. So you could have diarrhea or constipation or blood in the stool, anything that is a change. This change can affect frequency, color or consistency and there could be mucous. Sometimes there is a nagging discomfort or an increase in flatulence (gas). Sometimes large bowel problems are familial.