Bleeding from the rectum or blood in the stool is among the most common initial symptoms of rectal cancer. Changes in bowel movements, such as constipation, diarrhea, or excessive gas, can also be an early sign of rectal cancer.

Rectal cancer symptoms generally include:

* Bleeding from the rectum or blood in the stool
* Changes in bowel movements, such as constipation, diarrhea, or excessive gas
* Mucus in the stool
* Feeling of incomplete bowel evacuation
* Pain during bowel movements
* Severe abdominal pain and cramping
* Pencil-thin stools
* Unexplained weight loss
* Shortness of breath
* Dizziness