Long-term treatment with streptozocin/5-fluorouracil chemotherapy in patients with metastatic pancreatic neuroendocrine tumors Case series

Rationale: Pancreatic neuroendocrine tumors (pNETs) are rare entities representing 1% to 3% of all malignant pancreatic neoplasms. Current guidelines recommend a combination of streptozocin (STZ) and 5-fluorouracil (5-FU) for patients with metastatic well-differentiated pNETs requiring systemic therapy. The highest median progression-free survival rate reported in previous studies for this combination was 23 months (95% confidence interval 14.5-31.5). However, it remains unclear for how long this regimen can be safely administered. Patient concerns: We report about 3 therapy-naive patients with metastatic G2 (Ki67 10%-15%) pNETs treated with STZ/5-FU, that achieved sustained disease control for longer than 36 months. Diagnosis: Metastatic, well-differentiated G2 pNETs Interventions: Systemic chemotherapy with STZ/5-FU was administered until the disease progressed. In 1 case showing a mixed response, selected metastases of increasing size were additionally treated with surgery and brachytherapy. Outcomes: In our 3 patients with metastatic G2 pNETs, STZ/5-FU induced long-term disease control over 44, 42, and 95 months, respectively. No side effects that led to treatment discontinuation were observed. Lessons: In patients with metastatic G2 pNETs achieving disease control, STZ/5-FU can be safely administered.