Two consecutive run-in cohorts will administer pembrolizumab or pembrolizumab with SRT of 12 Gy to the lateral aspect of the primary tumor. Patients will receive pembrolizumab for 2 cycles prior to surgery or SRT and surgery. Surgical resection of all involved areas of tumor will occur within 6 weeks of the last administration of pembrolizumab. It should be noted that surgery is expected to occur within a much shorter window and 6 weeks would represent the greatest allowable amount of delay.