Can tumor absorbed dose predict response to Peptide Receptor Radionuclide Therapy (PRRT) in patients with gastroenteropancreatic neuroendocrine tumors (GEP-NETs)?

#3563

Introduction: Tumor dosimetry protocols following Peptide Receptor Radionuclide Therapy (PRRT) have not yet been standardised and tumor absorbed dose does not hold clear value in predicting response to treatment.

Aim(s): To prospectively correlate 68Ga-DOTATATE PET parameters and anatomical response to tumor absorbed doses to assess a possible dose-response relationship for GastroEnteroPanceratic-NeuroEndocrine Tumor patients treated with 177Lu-PRRT.

Materials and methods: Patients with advanced GEP-NETs treated with 177Lu-PRRT underwent 68Ga-DOTATATE PET/CT at baseline and 1-3 weeks before each cycle. Up to five target lesions (TL) per patient (RECIST 1.1 measurable) were selected on baseline CT/MRI. TLs were delineated on all PET images (PETEdge Tool, MIM Software) to calculate SUVmax and its %changes, as well as on serial SPECT/CT at 4h, 24h, and 7 days post-PRRT (region-growing method) for TL dosimetry. Longest axial diameter was documented on all CTs/MRIs to assess morphological response as per RECIST 1.1.

Conference:

Presenting Author: Mileva M

Authors: Mileva M, Marin G, Levillain H, van Bogaert C, Critchi G,

Keywords: PRRT, tumor dose, 68Ga-DOTATATE, SUVmax, response,