Top Line: Can PSMA-PET kinetics complement PSA surveillance following prostate ultra-hypofractionation?
The Study: A prospective phase 2 trial uniquely performed serial PSMA-PET imaging at baseline, radiation completion, 3-6 months and 9-12 months to identify imaging patterns we would otherwise never see. It enrolled 30 patients with intermediate (54%) and high (46%) risk prostate cancer receiving ultra-hypofractionated radiation with 36.25 Gy delivered to entire prostate and 40–42.5 Gy to PSMA-PET/MRI–guided dominant intraprostatic lesion all in 5 fractions concurrent to 6 months of ADT. Median baseline PSA was 13.7 ng/mL and median SUVmax was 9.9 at dominant lesion. PSA declined rapidly: median values fell to 0.02 ng/mL at 3 months and 0.03 ng/mL at 6 months, with 79% achieving PSA < 0.1 ng/mL at 6 months. PSMA-PET responses evolved more gradually: median SUVmax dropped to 3.18 at 3–6 months and 0 by 12 months. Complete PET response rates increased from 17% at treatment completion to 48% at 3–6 months and 65% at 9–12 months. Early PSMA “flare” occurred in 14% but resolved in most cases by 1 year. Importantly, patients achieving PSA < 0.1 ng/mL at 6 months were significantly more likely to demonstrate PSMA-PET complete response at 12 months (76% vs 28%, p=0.003).
TBL: While the majority of men will see a complete PSA response within 3-6 months of completing ultra-hypofractionated prostate radiation with concurrent ADT, it will take most men up to one year to see a complete response on PSMA-PET. | Singh, Int J Radiat Oncol Biol Phys 2026
The Study: A prospective phase 2 trial uniquely performed serial PSMA-PET imaging at baseline, radiation completion, 3-6 months and 9-12 months to identify imaging patterns we would otherwise never see. It enrolled 30 patients with intermediate (54%) and high (46%) risk prostate cancer receiving ultra-hypofractionated radiation with 36.25 Gy delivered to entire prostate and 40–42.5 Gy to PSMA-PET/MRI–guided dominant intraprostatic lesion all in 5 fractions concurrent to 6 months of ADT. Median baseline PSA was 13.7 ng/mL and median SUVmax was 9.9 at dominant lesion. PSA declined rapidly: median values fell to 0.02 ng/mL at 3 months and 0.03 ng/mL at 6 months, with 79% achieving PSA < 0.1 ng/mL at 6 months. PSMA-PET responses evolved more gradually: median SUVmax dropped to 3.18 at 3–6 months and 0 by 12 months. Complete PET response rates increased from 17% at treatment completion to 48% at 3–6 months and 65% at 9–12 months. Early PSMA “flare” occurred in 14% but resolved in most cases by 1 year. Importantly, patients achieving PSA < 0.1 ng/mL at 6 months were significantly more likely to demonstrate PSMA-PET complete response at 12 months (76% vs 28%, p=0.003).
TBL: While the majority of men will see a complete PSA response within 3-6 months of completing ultra-hypofractionated prostate radiation with concurrent ADT, it will take most men up to one year to see a complete response on PSMA-PET. | Singh, Int J Radiat Oncol Biol Phys 2026