Testing the Use of Chemotherapy After Surgery for High-Risk Pancreatic Neuroendocrine Tumors

PRIMARY OBJECTIVE: I. To evaluate recurrence-free survival (RFS) in participants with resected pancreatic neuroendocrine tumors (pNETs) randomized to treatment with capecitabine + temozolomide (CAPTEM) compared to observation only. SECONDARY OBJECTIVES: I. To evaluate overall survival (OS) in participants randomized to treatment with CAPTEM compared to observation only. II. To evaluate the safety and tolerability of CAPTEM compared to observation only. BANKING OBJECTIVE: I. To bank specimens for future correlative studies. OUTLINE: Patients are randomized to 1 of 2 arms. ARM I: Patients receive capecitabine orally (PO) twice daily (BID) on days 1-14 and temozolomide PO once daily (QD) on days 10-14. Treatment repeats every 28 days for up to 4 cycles in the absence of disease progression or unacceptable toxicity. ARM II: Patients undergo surveillance with no active treatment. After completion of study treatment, patients are followed up every 6 months for 3 years and then annually until 5 years from randomization.