PSMA PET/CT in biochemical recurrence of prostate cancer with PSA levels ≤ 0.2 ng/mL: a German multicenter analysis of conventional PSMA tracers, including [68Ga]Ga-PSMA-11, [68Ga]Ga-PSMA I&T, and [18F]PSMA-1007.

BACKGROUND: Prostate-specific membrane antigen (PSMA)-directed positron emission tomography/computed tomography (PET/CT) has emerged as a highly accurate imaging modality for detecting tumor lesions in patients with biochemical recurrence (BCR) of prostate cancer (PC). While detection rates of lesions suspicious for PC relapse are known to increase with rising prostate-specific antigen (PSA) levels, data on the efficacy of PSMA PET/CT at very low PSA values (≤ 0.2 ng/mL) remain limited.

METHODS: In this multicenter study, we analyzed 321 patients with BCR and a PSA value ≤ 0.2 ng/mL across five German academic centers, using three different PSMA-targeted radiotracers: [68Ga]Ga-PSMA-11, [68Ga]Ga-PSMA I&T, and [18F]PSMA-1007 and analyzed the detection rates and potential predictive parameters.

RESULTS: The overall pooled detection rate was 29.6%. No statistically significant differences in detection rates were observed between the three radiotracers ([68Ga]Ga-PSMA-11 29.4% vs. [68Ga]Ga-PSMA I&T, 22.5% vs. [18F]PSMA-1007 32.4%, p ≥ 0.314). Detection rates were significantly higher in patients with a PSA level > 0.15 ng/mL (p = 0.029, φ = 0.122), in those with an initial Gleason score > 7 (p = 0.018, φ = 0.141) and in those receiving androgen deprivation therapy (p = 0.031, φ = 0.120).

CONCLUSION: All three radiotracers demonstrated comparable diagnostic performance, with no significant superiority observed between the 68Ga- and 18F-labeled tracers in the patient sample investigated (overall pooled detection rate: 29.6%). This positivity rate can serve as an expectation horizon for both the attending physician and the patient in the case of low PSA values. Further studies with larger cohorts, preferably conducted in a prospective setting, are needed to confirm and expand upon our findings.