Abstract
1175
Objectives Outcome analyses after peptide receptor radionuclide therapy (PRRT) are still limited, especially with regard to the impact of the Ki-67 index. We aim to establish predictors of survival.
Methods Retrospective analysis of 74 consecutive GEP NET pts undergoing PRRT with 177Lu-octreotate. Patients had unresectable metastatic disease and a G1/2 grading (33 pancreatic, 41 non-pancreatic GEP-NET), documented morphologic or clinical progression within < 12 months and/or uncontrolled disease. Response (modified SWOG criteria) was correlated with potential impact factors: origin, function, burden, and uptake of tumor, age, Ki-67-index, Karnofsky score, baseline tumor marker levels. Predictors for survival were analyzed with Kaplan-Meier curves (log-rank test) and multivariate analysis (p<0.05).
Results The response rates were 36.5% PR, 17.6% MR, 35.1% SD, and 10.8% PD for the entire cohort, 54.5% PR, 18.2% MR, 18.2% SD, and 9.1% PD for pancreatic NET, and 22.0% PR, 17.1% MR, 48.8% SD, and 12.2% PD for non-pancreatic GEP-NET. The median progression-free (PFS) and overall (OS) survival was 26 months (95% CI, 18.3 - 33.7) and 55 months (95% CI, 48.8-61.2), respectively. The only factor associated with decreased PFS was a Ki-67 index >10% (p=0.002). For OS, besides the Ki-67 index, a Karnofsky score ≤70% and a baseline NSE of >15 ng/ml independently predicted shorter survival (each p<0.005, HR 3.0 - 3.4). Patients with a Ki-67 index >10% still had a median PFS and OS of 19 and 34 months, respectively.
Conclusions This study demonstrates the very favorable outcome of G1/2 NET after PRRT. Independent predictors of survival are the Ki-67 index, the patient‘s performance status and the baseline NSE level. Nevertheless, patients with a Ki-67 >10% still benefit from PRRT with good response and a notable long-term outcome when compared to other treatment forms