RT Journal Article SR Electronic T1 [18F]FDG PET/CT–Avid Discordant Volume as a Biomarker in Patients with Gastroenteropancreatic Neuroendocrine Neoplasms: A Multicenter Study JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 185 OP 191 DO 10.2967/jnumed.123.266346 VO 65 IS 2 A1 Chan, David L. A1 Hayes, Aimee R. A1 Karfis, Ioannis A1 Conner, Alice A1 Mileva, Magdalena A1 Bernard, Elizabeth A1 Schembri, Geoffrey A1 Navalkissoor, Shaunak A1 Gnanasegaran, Gopinath A1 Pavlakis, Nick A1 Marin, Clémentine A1 Vanderlinden, Bruno A1 Flamen, Patrick A1 Roach, Paul A1 Caplin, Martyn E. A1 Toumpanakis, Christos A1 Bailey, Dale L. YR 2024 UL http://jnm.snmjournals.org/content/65/2/185.abstract AB [18F]FDG PET/CT and [68Ga]Ga-DOTATATE PET/CT are both used to predict tumor biology in neuroendocrine neoplasms. Although the presence of discordant ([18F]FDG-avid/non–[68Ga]Ga-DOTATATE–avid) disease predicts poor prognosis, the significance of the volume of such discordant disease remains undetermined. The aim of this study is to investigate discordant tumor volume as a potential biomarker in patients with advanced gastroenteropancreatic neuroendocrine neoplasms (GEPNENs). Methods: A multicenter retrospective study in patients with advanced GEPNENs and paired [18F]FDG and [68Ga]Ga-DOTATATE PET/CT no more than 85 d apart was conducted. Patients with discordant disease were identified by the NETPET score, and discordant lesions were contoured with a flat [18F]FDG SUV cutoff of 4. The primary variable of interest was the total discordant volume (TDV), which was the sum of the volumes of discordant lesions. Patients were dichotomized into high- and low-TDV cohorts by the median value. The primary endpoint was overall survival. Results: In total, 44 patients were included (50% men; median age, 60 y), with primary cancers in the pancreas (45%), small bowel (23%), colon (20%), and other (12%). Of the patients, 5% had grade 1 disease, 48% had grade 2 disease, and 48% had grade 3 disease (24% well differentiated, 67% poorly differentiated, 10% unknown within the grade 3 cohort). The overall median survival was 14.1 mo. Overall survival was longer in the low-TDV cohort than in the high-TDV cohort (median volume, 43.7 cm3; survival time, 23.8 mo vs. 9.4 mo; hazard ratio, 0.466 [95% CI, 0.229–0.948]; P = 0.0221). Patients with no more than 2 discordant intrahepatic lesions survived longer than those with 2 or more lesions (31.8 mo vs. 10.2 mo, respectively; hazard ratio, 0.389 [95% CI, 0.194–0.779]; P = 0.0049). Conclusion: TDV is a potential prognostic biomarker in GEPNENs and should be investigated in future neuroendocrine neoplasm trials.