Possible signs of colorectal cancer include:

• a change in the frequency of bowel movements

• diarrhea, constipation, or feeling that the bowel does not empty completely

• either bright red or very dark blood in the stool

• stools that are narrower than usual

• general abdominal discomfort such as frequent gas pains, bloating, fullness, and/or cramps

• weight loss with no known reason

• constant tiredness

• vomiting