319 Background: Biochemical recurrence (BCR) of prostate cancer (PCa) is traditionally defined by the Phoenix criterion (PSA rise ≥ 2 ng/ml above nadir). However, prostate-specific membrane antigen (PSMA) PET/CT can identify recurrent or metastatic disease at much lower PSA levels. This study evaluated the detection rate and clinical relevance of PSMA PET/CT across varying PSA values in patients with PCa following curative-intent radiotherapy (RT). Methods: We retrospectively analysed 182 patients managed between January 2021 and December 2024 who received curative-intent RT for PCa. Clinical data included PSA at the time of imaging, Gleason score, disease distribution, and prior primary treatment. Results: Of 182 patients, 167 (91.7%) underwent PSMA PET/CT; 149 (81.8%) demonstrated PSMA-avid lesions indicating local recurrence and/or metastatic disease, while 18 (9.8%) had negative scans. Thirty patients (17.9%) did not meet the Phoenix criterion (PSA 2 but 3 but < 4 ng/ml; 6 (33.3%) had nodal metastases, 6 (33.3%) bone metastases, 3 (16.6%) nodal plus bone disease, and 2 (11.1%) visceral metastases. Within this group, 44.4% had Gleason 9 and 38.8% had Gleason 7 disease. Conclusions: PSMA PET/CT demonstrates high sensitivity for detecting recurrent and metastatic PCa even at PSA ≤ 4 ng/ml, identifying disease in over 40% of scanned patients. Detection of nodal and distant metastases below the Phoenix threshold challenges the current reliance on biochemical criteria to trigger imaging. Early PSMA PET/CT may enable prompt therapeutic intervention and improved clinical outcomes. Prospective studies are warranted for validation.
Das et al. (Sun,) studied this question.