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.
This phase II trial studies the effect of capecitabine and temozolomide after surgery in treating patients with high-risk well-differentiated pancreatic neuroendocrine tumors. Chemotherapy drugs, such as capecitabine and temozolomide, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Giving capecitabine and temozolomide after surgery could prevent or delay the return of cancer in patients with high-risk well-differentiated pancreatic neuroendocrine tumors.