Study of Pembrolizumab, Carboplatin, Paclitaxel, and Radiation for the Treatment of Early-Stage Anal Cancer

This trial is studying whether adding the immunotherapy drug pembrolizumab to the standard chemoradiation treatment for early-stage anal cancer can improve cure rates while staying safe. **You may be eligible if...** - You are 18 or older - You have been diagnosed with early-stage squamous cell carcinoma of the anus (Stage I through IIIA) - You are in generally good health and able to carry out daily activities (ECOG 0–1) - You have not received prior treatment for this cancer - Your blood counts and organ function are within acceptable ranges **You may NOT be eligible if...** - You have Stage IIIB or Stage IV (very advanced) anal cancer - You have previously received chemotherapy or radiation for anal cancer - You have active autoimmune disease or are on immune-suppressing medications - You are pregnant or breastfeeding - You have had a major surgery in the past month Talk to your doctor to see if this trial is right for you.