Streptozocin/5-fluorouracil chemotherapy is associated with durable response in patients with advanced pancreatic neuroendocrine tumours

Background: The role of systemic chemotherapy for pancreatic neuroendocrine tumours (pNET) is controversially discussed. Objective response rates (RR) reported for streptozocin (STZ)-based chemotherapy are variable and novel targeted drugs have recently been approved. However, the sequence of treatment remains unclear. We aimed to evaluate the efficacy of STZ plus 5-fluorouracil (STZ/5-FU) in a large pNET cohort.

Methods: Data from 96 pNET patients treated with STZ/5-FU were analysed retrospectively. Endpoints of the study were RR, time to tumour progression (TTP) and overall survival (OS).

Results: Mean age of patients at the start of chemotherapy was 57.6years (range, 32.1-80.4). STZ/5-FU was the 1st line treatment in 56.3%. 11.5% had G1, 79.2% G2 and 6.3% G3 neoplasms. Baseline progression was evident in 74%. Objective response rate was 42.7%. 40.6% of patients showed stable disease as best response while 16.7% showed progressive disease. Treatment was discontinued due to toxicity in 16 patients. Median TTP and OS were 19.4 (95% confidence interval (CI), 13.6-25.2) and 54.8months (95% CI, 34.7-74.9), respectively. In Cox regression analysis, Ki67>15% was the only negative prognostic factor for TTP (hazard ratio (HR), 3.3; P<0.001), confirmed by multivariate analysis (HR, 6.7; P=0.001).

Conclusions: STZ/5-FU was associated with considerable RR. Treatment was associated with durable TTP especially in patients with Ki67-index of ⩽15%. These findings along with good tolerability strengthen the value of this two-drug chemotherapy for the management of unresectable pNET.