Detection Efficacy of ⁶⁸Ga-PSMA-11 PET/CT in Biochemical Recurrence of Prostate Cancer with Very Low PSA Levels: A 7-Year, Two-Center “Real-World” Experience

Abstract

In biochemical recurrence of prostate cancer (BCR), prompt tumor localization guides early treatment, potentially improving patient outcomes. Gallium-68 prostate-specific membrane antigen-11 positron emission tomography/computed tomography (68Ga-PSMA-11 PET/CT) detection rates of lesions suspicious for prostate cancer are well known to rise along with prostate-specific antigen (PSA) concentration. However, published data are limited regarding very low values (≤0.2 ng/mL). We retrospectively analyzed ~7-year “real-world” experience in this setting in a large post-prostatectomy cohort (N = 115) from two academic clinics. Altogether 44 lesions were detected in 29/115 men (25.2%) (median [minimum–maximum] 1 [1–4]/positive scan). The apparent oligometastatic disease was found in nine patients (7.8%) at PSA as low as 0.03 ng/mL. Scan positivity rates were highest when PSA was >0.15 ng/mL, PSA doubling time was ≤12 months, or the Gleason score was ≥7b (in 83 and 107 patients, respectively, with available data); these findings were statistically significant (p ≤ 0.04), except regarding PSA level (p = 0.07). Given the benefits of promptly localizing recurrence, our observations suggest the potential value of 68Ga-PSMA-11 PET/CT in the very low PSA BCR setting, especially in cases with more rapid PSA doubling time or with high-risk histology.

Keywords

• prostate cancer
• biochemical recurrence
• low serum prostate-specific antigen (PSA) concentration
• gallium-68 prostate-specific membrane antigen-11 positron emission tomography (⁶⁸Ga-PSMA-11 PET/CT)
• detection rate
• PSA doubling time