A total of approximately 40 patients at up to 30 clinical sites will be screened for eligibility into the study within 6 weeks of completing treatment, including R0 (complete resection with no microscopic residual tumor) or R1 (complete resection with no grossly visible tumor but microscopically positive margins) surgery for stage I or stage II adenocarcinoma of the pancreas with or without chemotherapy and radiation. Eligible patients must have no measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 (Eisenhauer 2009) and tumor marker carbohydrate antigen 19-9 [CA 19-9] not greater than 2 × the upper limit of normal (ULN) following surgery with or without chemotherapy or radiation. Prior surgery, neoadjuvant chemotherapy, adjuvant chemotherapy, and radiation therapy are allowed.