The management impact of ⁶⁸gallium-tris(hydroxypyridinone) prostate-specific membrane antigen (⁶⁸Ga-THP-PSMA) PET-CT imaging for high-risk and biochemically recurrent prostate cancer.

Abstract

Purpose To determine the impact on clinical management of patients with high-risk (HR) prostate cancer at diagnosis and patients with biochemical recurrence (BCR) using a new kit form of ⁶⁸Ga-prostate-specific membrane antigen (PSMA), namely tris(hydroxypyridinone) (THP)-PSMA, with positron emission tomography-computed tomography (PET-CT). Methods One hundred eighteen consecutive patients (50 HR, 68 BCR) had management plans documented at a multidisciplinary meeting before ⁶⁸Ga-THP-PSMA PET-CT. Patients underwent PET-CT scans 60-min post-injection of ⁶⁸Ga-THP-PSMA (mean 159 ± 21.2 MBq). Post-scan management plans, Gleason score, prostate-specific antigen (PSA) and PSA doubling time (PSAdt) were recorded. Results HR group: 12/50 (24%) patients had management changed (9 inter-modality, 3 intra-modality). Patients with PSA 20 μg/L (3/24, 12.5%). Gleason scores > 8 were associated with detection of more nodal (4/16, 25% vs 5/31, 16.1%) and bone (2/16, 12.5% vs 2/31, 6.5%) metastases. BCR group: Clinical management changed in 23/68 (34%) patients (17 inter-modality, 6 intra-modality). Forty out of 68 (59%) scans were positive. Positivity rate increased with PSA level (PSA 8 (78.9% vs 51.2%). Conclusions ⁶⁸Ga-THP-PSMA PET-CT influences clinical management in significant numbers of patient with HR prostate cancer pre-radical treatment and is associated with PSA. Management change also occurs in patients with BCR and is associated with PSA and Gleason score, despite lower scan positivity rates at low PSA levels < 0.5 μg/L.