Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Anal Cancer ?
    ### Response:
    Key Points
				                    - Anal cancer is a disease in which malignant (cancer) cells form in the tissues of the anus.    - Squamous cell carcinoma is the most common type of anal cancer.    - In the United States, the number of new cases of anal cancer has increased in recent years.
    