NEOADJUVANT TREATMENT: Patients receive pembrolizumab intravenously (IV) over 30 minutes on days -7, 15, and 36 and carboplatin IV and paclitaxel IV over 1-96 hours on days 1, 8, 15, 22 and 29. Patients also undergo radiation therapy once daily (QD) 5 days per week for 4 weeks and 3 days (23 fractions).