Colorectal cancers may not present any symptoms at first, however, when they do, following are seen;

Changes in bowel movement like diarrhea, constipation or thinning in the stool and these being persistent for more than a few days

Feeling the need of defecation, however, continued sense of defecation afterwards

Bleeding from the anus

Bloody stool

Abdominal pain or cramps

Weakness, fatigue

Unintended weight loss

Colorectal cancers frequently cause bleeding into the digestive system. Blood may appear as mixed with stool or by making the stool appear darker; although stool might look normal as well. However, this invisible chronic blood loss may cause anemia in time. Sometimes first finding of colorectal cancer might be anemia diagnosis.