Parameters to Predict Progression-Free and Overall Survival After Peptide Receptor Radionuclide Therapy: A Multivariate Analysis in 782 Patients

Peptide receptor radionuclide therapy (PRRT) is an effective treatment for patients with neuroendocrine neoplasms. The aim of this study was to identify clinical and treatment parameters associated with progression-free survival (PFS) and overall survival (OS). Methods: All patients treated from October 2002 until March 2016 at the Zentralklinik Bad Berka with at least 3 administrations of PRRT (maximal interval of 6 mo between consecutive administrations) were included. Data were collected in 5 categories: general patient characteristics, tumor characteristics, prior treatments, radioisotope used for PRRT, and blood chemistry. Survival was analyzed using Kaplan-Meier curves. Univariate and multivariate Cox regression analyses were performed to identify parameters associated with PFS and OS. Results: In total, 782 patients were included, with a median follow-up of 36 mo. The median PFS and OS were 22 and 53 mo, respectively. Parameters associated with lower PFS in the multivariate analysis were a Ki-67 of more than 5%, previous treatment with interferon-alpha and chemotherapy, presence of diabetes, and chromogranin-A (CgA) levels higher than 336 mu g/L. Parameters associated with lower OS were a Ki-67 of more than 10%, performance status of at least 1, previous chemotherapy and ablation, and CgA levels higher than 112 mu g/L. Conclusion: Higher Ki-67 values, as well as higher CgA levels and previous chemotherapy, had a negative outcome on both PFS and OS. Furthermore, PFS was negatively associated with previous interferon-alpha treatment and diabetes, whereas lower OS was related to prior ablation and higher performance status.