Abstract
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Objectives We evaluated long-term efficacy and toxicity of tailored 177Lu-dotatate (177Lu-PRRT) therapy in 65 consecutive patients with G1-G2 pancreatic neuroendocrine tumors (P-NENs).The role of 18F-FDG PET-CT as an independent prognostic factor was also investigated.
Methods From March 2008 to September 2011, 65 consecutive P-NEN patients were enrolled in a prospective study and followed-up until March 2015. Patients were treated with two different total activities (18.5GBq or 27.8 GBq) and underwent 5 cycles of 177Lu-PRRT depending on the kidney and bone marrow status. Fifty-nine patients underwent 18F-FDG PET-CT before 177Lu-PRRT.
Results Median follow-up was 59 months (7-82). Thirty patients received a mean full activity (FA) of 25.5 GBq (20.7-27.8) and 35 a mean reduced activity (RA) of 17.8 GBq (11.1-19.9). The disease control rate (DCR) in the FA group was 87% and 85% in the RA group (p=0.83). Median progression-free survival (PFS) was 53.4 months (21.2-68.7) in the FA arm and 24.4 months (19.5-59.2) in the RA arm (p= 0.42). Median overall survival (OS) was not reached in FA patients and was 63.8 months in the RA group (p= 0.013). No cases of grade 3 or 4 hematological toxicity were registered. One (3%) RA patient showed grade 2 renal toxicity and another (3%), grade 3 renal toxicity. Median PFS in the PET-CT-positive group was 21.2 months (18.9-28.7) compared to 68.7 months in PET-CT-negative patients (53.4-nr) (p <0.0003), regardless of the total activity administered. Median OS was not reached in the negative PET-CT group and was 63.8 months in the positive PET-CT group (p= 0.005).
Conclusions Personalized 177Lu-PRRT showed effective antitumor activity and mild toxicity in advanced P-NEN patients, and was feasible in patients with severe comorbidities. 18F-FDG PET-CT was confirmed as a valid independent prognostic factor in these patients.