Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Rectal Cancer ?
    ### Response:
    Key Points
                    - Rectal cancer is a disease in which malignant (cancer) cells form in the tissues of the rectum.     - Health history affects the risk of developing rectal cancer.    - Signs of rectal cancer include a change in bowel habits or blood in the stool.
    