- Patients who have been treated with any combination of surgical resection and neoadjuvant/adjuvant conventional chemoradiation therapy for resectable disease or conventional chemoradiation as definitive treatment for unresectable or borderline resectable disease are eligible for the study, provided that at least 180 days have elapsed since completing any previous radiation treatment. Patients who have been receiving continued chemotherapy following their initial radiation treatment are eligible regardless of when the most recent chemotherapy was received. Those patients who have received prior radiation therapy will constitute Cohort A and will receive stereotactic body radiation (SBRT) as 5 gray (Gy) x 5.