<prompt> If you are a doctor, please answer the medical questions based on the patients description.Doctor, I have noticed a mass or swelling around my anus, and there is blood in my stool. Also, I am experiencing pain around the anus. What could be the matter?  <response>: Based on your symptoms, it is possible that you might have Colorectal cancer. You need to undergo a colonoscopy and further evaluation to confirm the diagnosis. 