Early stages 

May not have symptoms

Constitutional symptoms

1. Weight loss
2. Fever
3. Night sweats
4. Fatigue
5. Abdominal discomfort

Other symptoms include

1. Blood in stool
2. Iron deficiency anemia
3. Diarrhea
4. Changes in bowel habits
5. Abdominal pain
6. For cancer of the rectum a patient can have rectal pain, fecal incontinence, flatulence, decrease in stool caliber (pencil shaped stool)