RT Journal Article SR Electronic T1 PSMA PET for the Assessment of Metastatic Hormone-Sensitive Prostate Cancer Volume of Disease JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1747 OP 1750 DO 10.2967/jnumed.121.262120 VO 62 IS 12 A1 Barbato, Francesco A1 Fendler, Wolfgang P. A1 Rauscher, Isabel A1 Herrmann, Ken A1 Wetter, Axel A1 Ferdinandus, Justin A1 Seifert, Robert A1 Nader, Michael A1 Rahbar, Kambiz A1 Hadaschik, Boris A1 Eiber, Matthias A1 Gafita, Andrei A1 Weber, Manuel YR 2021 UL http://jnm.snmjournals.org/content/62/12/1747.abstract AB Conventional imaging of low-volume disease (LVD) versus high-volume disease (HVD) is associated with survival in metastatic hormone-sensitive prostate cancer (mHSPC) according to the CHAARTED trial (Chemohormonal Therapy in Metastatic Hormone-Sensitive Prostate Cancer) and the STAMPEDE trial (Systemic Therapy for Advanced or Metastatic Prostate Cancer: Evaluation of Drug Efficacy). We propose a compatible quantitative PSMA PET framework for disease volume assessment in mHSPC. Methods: Three PET centers screened their PSMA PET database for mHSPC patients. CT versus PSMA PET stage, lesion number, and classification of LVD versus HVD were determined by 1 masked reader; PSMA-positive tumor volume was quantified semiautomatically. Results: In total, 85 CT-based CHAARTED LVD and 20 CT-based CHAARTED HVD patients were included. A PSMA tumor volume of about 40 cm3 was the optimal cutoff between CT-based CHAARTED LVD (nonunifocal) and HVD (non-M1c) (area under the curve, 0.86). Stratification into PET LVD (unifocal or oligometastatic/disseminated < ∼40 cm3) and PET HVD (oligometastatic/disseminated ≥ ∼40 cm3 or M1c) had 13% misalignment with the CHAARTED criteria. Conclusion: PSMA PET criteria with volume quantification deliver comparable LVD/HVD discrimination with additional subgroups for unifocal, oligometastatic, and disseminated disease, critical for guidance of targeted or multimodal therapy.