The outcome of peptide receptor radionuclide therapy (PRRT) in North American patients with advanced well-differentiated neuroendocrine tumors (WD-NETs).

Abstract

e14600 Background: PRRT is frequently used in Europe for patients with advanced WD-NETs, but it is not yet readily available in the USA. We analyzed data on 135 North American patients seen at our institution who underwent PRRT. Methods: Cases were identified by searching the University of Iowa Neuroendocrine Tumors Database. Groups were compared using a Wilcoxon rank-sum test, and survival was calculated with the Kaplan-Meier method. Results: Men were 64%, women 36%; median age at diagnosis was 51 years (18 – 78). The primary tumor originated in the small bowel (SBNET) in 37.8%, pancreas (PNET) 26.0%, lung 13.3%, unknown primary 9.6%, other sites 13.3%. PRRT was performed at the University of Basel, Switzerland in 68.8%, University of Iowa in 25.2%, and elsewhere in 6%. 90Y was used in 83.2% and 177Lu in 15.3% for the first PRRT. Median dose of radiation was 180 mCi (range 7.6 – 360). 116 patients received two treatments with median time between the treatments 2.1 months (range 0.4 – 110). Survival is shown in the table. Radiographic responses (any) at 1-6 months after PRRT were observed in 65.8%, 11.1% had a mixed response, and 15.4% progressed. A biochemical response (>50% reduction in chromogranin A and pancreastatin levels) was seen in 18% and 17.3% respectively but data was frequently missing. Conclusions: North American patients with WD-NETs have a relatively long survival. The OS from 1st PRRT was much less than OS after diagnosis, suggesting that PRRT is used late in the disease course. PRRT appears to be a valuable treatment option for WD-NETs, especially SBNETS, and its role earlier in the disease course warrants investigation. [Table: see text]