Consort diagram of the study population. At the beginning of the analyses 421 patients, treated with peptide receptor radionuclide therapy (PRRT), were assessed. Patients who did not meet the inclusion criteria were excluded. These were mainly patients with pulmonary NET, NET with unknown primary, G3-tumors and patients with overall-follow up of < 6 months. Depending on the therapy protocol the study population was divided into two groups. Group 1 was patients, who underwent a peptide receptor radionuclide therapy (PRRT) as a monotherapy and received no maintenance therapy with SSA. In group 2, patients received a maintenance therapy with SSA after a monotherapy with PRRT or underwent a PRRT combined with SSA, followed by a maintenance therapy with SSA. A pre-treatment with SSA was allowed in both groups. Patients who could not be clearly classified into these groups were excluded.
ARTICLE ABSTRACT
Purpose: Although somatostatin analogues (SSA) and peptide receptor radionuclide therapy (PRRT) are validated therapies in patients with advanced gastroenteropancreatic neuroendocrine tumors (GEP-NET), it remains unclear whether SSA combined with PRRT or as maintenance therapy can provide prolonged survival compared with patients treated with PRRT alone. In this retrospective study, we aimed to investigate whether there is a survival benefit to adding SSA to PRRT as a combination therapy and/or maintenance therapy.Patients and Methods: The investigation included 168 patients with unresectable GEP-NETs treated at the University Hospital Bonn, Bonn, Germany. The patients were divided into two main groups: PRRT monotherapy (N = 81, group 1) and PRRT plus SSA (N = 87, group 2) as combined therapy with PRRT and/or as maintenance therapy after PRRT.Results: Data for overall survival (OS) were available from 168 patients, of whom 160 had data for progression-free survival (PFS). The median PFS was 27 months in group 1 versus 48 months in group 2 (P = 0.012). The median OS rates were 47 months in group 1 and 91 months in group 2 (P < 0.001). The death-event rates were lower in group 2 (26%) than in group 1 (63%). SSA as a combination therapy with PRRT and/or as a maintenance therapy showed a clinical benefit rate (objective response or stable disease) of 95%, which was significantly higher than group 1 (79%).Conclusions: SSA as a combination therapy and/or maintenance therapy may play a significant role in tumor control in patients with GEP-NET who underwent a PRRT. Clin Cancer Res; 24(19); 4672–9. ©2018 AACR.
