Extended cycle streptozotocin/5-FU chemotherapy for maintenance therapy in pancreatic neuroendocrine tumors

Purpose The standard of care treatment for patients with advanced pancreatic neuroendocrine tumors (pNET) is a combination of streptozotocin and 5-FU. Although widely used, little is known about the best long-term strategy with these substances. Methods We here report our experience of 28 patients treated with streptozotocin/5-FU for advanced pNET with special consideration for long-term management using an extended cycle protocol. Results Standard 6-weekly Moertel protocol resulted in a median progression-free survival of 21 months (range 3–128) and a median overall survival of 69 months (range 3–157+) in the whole cohort. Thirteen of the 28 patients were switched to an extended 3-month cycle protocol for maintenance therapy. Of these 13 patients, 2 achieved complete remission, 1 partial remission, and 8 stable disease as best response while 2 showed progressive disease following switch to the extended protocol, resulting in an additional median progression-free survival of 23 months. Median overall survival after the start of chemotherapy in this patient group was 69 months (21–157+). Patients benefitted from extended periods free of chemotherapy-associated side effects after switching to the extended cycle protocol. Conclusions Switching to an extended cycle protocol of 3 months for maintenance therapy following initial standard cycles may achieve long-term disease stabilization in selected patients with advanced pNET with good patient acceptance.