Efficacy of peptide receptor radionuclide therapy with 177Lu-octreotate in metastatic pulmonary neuroendocrine tumors: a dual-centre analysis.

There is lack of data on the specific benefit of peptide receptor radionuclide therapy (PRRT) in neuroendocrine tumors (NET) of pulmonary origin. This dual- centre study aimed to assess outcome and toxicity of standardized PRRT with 177Lu-octreotate in a patient population of advanced pulmonary NET of grade 1-2. We retrospectively assessed 22 consecutively patients treated with 4 intended cycles at 3 monthly intervals (mean activity per cycle 7.8±0.68 GBq). In a median follow-up period of 54 months, no significant nephrotoxicity (≥ grade 3) was observed. Reversible hematotoxicity (grade 3) occurred in 3 patients (13.6%). Treatment response consisted of partial response in 6 (27.3%), stable disease in 9 (40.9%), and progressive disease in 7 (31.8%) patients. Median progression-free survival (PFS) and overall survival (OS) was 27 (95% CI, 9-45) and 42 months (95% CI, 25-59), respectively. High hepatic tumor load (> 50%) and high plasma chromogranin A (> 600 ng/mL) were negative baseline predictors for PFS and OS on univariate analysis, CgA remained significant on multivariate analysis (PFS, P=0.011; OS, P=0.026). Disease progression despite PRRT was associated with shorter survival (median OS 15 vs 53 mo, P<0.001). Despite a higher incidence of treatment failure compared to NET of other origins, the observed substantial and sustained disease stabilization (median PFS of 27 mo, disease control rate of > 2/3 of pts) indicates considerable efficacy of 177Lu-octreotate in pulmonary NET.