PT  - JOURNAL ARTICLE
AU  - Pauwels, Elin
AU  - Van Binnebeek, Sofie
AU  - Vandecaveye, Vincent
AU  - Baete, Kristof
AU  - Vanbilloen, Hubert
AU  - Koole, Michel
AU  - Mottaghy, Felix M.
AU  - Haustermans, Karin
AU  - Clement, Paul M.
AU  - Nackaerts, Kristiaan
AU  - Van Cutsem, Eric
AU  - Verslype, Chris
AU  - Deroose, Christophe M.
TI  - Inflammation-based index and <sup>68</sup>Ga-DOTATOC PET-derived uptake and volumetric parameters predict outcome in neuroendocrine tumor patients treated with <sup>90</sup>Y-DOTATOC
AID  - 10.2967/jnumed.119.236935
DP  - 2019 Dec 01
TA  - Journal of Nuclear Medicine
PG  - jnumed.119.236935
4099  - http://jnm.snmjournals.org/content/early/2019/12/03/jnumed.119.236935.short
4100  - http://jnm.snmjournals.org/content/early/2019/12/03/jnumed.119.236935.full
AB  - We performed post-hoc analyses on the utility of pre-therapeutic and early interim 68Ga-DOTA-Tyr3-octreotide (68Ga-DOTATOC) positron emission tomography (PET) tumor uptake and volumetric parameters and a recently proposed biomarker, the inflammation-based index (IBI), for peptide receptor radionuclide therapy (PRRT) in neuroendocrine tumor (NET) patients treated with 90Y-DOTATOC in the setting of a prospective phase II trial. Methods: Forty-three NET patients received up to four cycles of 1.85 GBq/m²/cycle 90Y-DOTATOC with a maximal kidney biologic effective dose of 37 Gy. All patients underwent a 68Ga-DOTATOC PET/computed tomography (CT) at baseline and seven weeks after the first PRRT cycle. 68Ga-DOTATOC-avid tumor lesions were semi-automatically delineated using a customized standardized uptake value (SUV) threshold-based approach. PRRT response was assessed on CT using RECIST 1.1. Results: Median progression-free survival (PFS) and overall survival (OS) were 13.9 and 22.3 months, respectively. An SUVmean higher than 13.7 (75th percentile (P75)) was associated with better survival (hazard ratio (HR) 0.45; P = 0.024), whereas a 68Ga-DOTATOC-avid tumor volume higher than 578 ml (P75) was associated with worse OS (HR 2.18; P = 0.037). Elevated baseline IBI was associated with worse OS (HR 3.90; P = 0.001). Multivariate analysis corroborated independent associations between OS and SUVmean (P = 0.016) and IBI (P = 0.015). No significant correlations with PFS were found. A composite score based on SUVmean and IBI allowed to further stratify patients in three categories with significantly different survival. On early interim PET, a decrease in SUVmean of more than 17% (P75) was associated with worse survival (HR 2.29; P = 0.024). Conclusion: Normal baseline IBI and high 68Ga-DOTATOC tumor uptake predict better outcome in NET patients treated with 90Y-DOTATOC. This can be used for treatment personalization. Interim 68Ga-DOTATOC PET does not provide information for treatment personalization.