Clinical impact of 68Ga-PSMA-11 PET on patient management and outcome, including all patients referred for an increase in PSA level during the first year after its clinical introduction

Abstract

Purpose: The fast-increasing use of positron emission tomography (PET) with prostate-specific membrane antigen (PSMA) ligand for the imaging of prostate cancer (PCA) biochemical recurrence has led to a rapid change in treatment concepts. Since the superiority of ⁶⁸Ga-PSMA-11 PET in detecting recurrent PCA is well established, the aim of our study was to assess its effect on management and outcome in all patients imaged during the first year after its introduction into clinical routine.

Methods: Of 327 patients imaged, 223 were referred for recurrent PCA and gave written informed consent for further analysis of their data for this retrospective consecutive cohort analysis. Twenty patients were lost to further follow-up. The rate of detection of recurrence by ⁶⁸Ga-PSMA-11 PET was based on the clinical reports. Management before the availability of PET diagnostic information was assessed according to guidelines (therapy option without ⁶⁸Ga-PSMA-11 PET). In the 203 patients with follow-up 6 months after ⁶⁸Ga-PSMA-11 PET, the therapies effectively implemented as well as follow-up PSA levels were evaluated, with a PSA value of <0.2 ng/ml representing a complete response and a decrease in PSA value of at least 50% from baseline representing a partial response.

Results: ⁶⁸Ga-PSMA-11 PET was positive and identified recurrence in 166 of the 223 patients (74%), with a detection rate of 50% for recurrent disease at low PSA values of <0.5 ng/ml. ⁶⁸Ga-PSMA-11 PET led to a change in management in 122 of the 203 patients (60%). A substantial increase in the use of metastasis-targeted treatment and a reduction in the use of systemic treatment were observed, with 59 of the 203 patients (29%) undergoing targeted radiotherapy (RTXa) only, and 20 patients (10%) undergoing RTXa with hormonal therapy as the two most frequently selected therapy options. The proportion of patients in whom systemic therapy was selected decreased from 60% (133 of 223 patients) to 34% (70 of 203 patients) on the basis of the information provided by the ⁶⁸Ga-PSMA-11 PET scan. PSMA PET-directed metastasis-targeted treatment led to a complete response after 6 months in 45% of patients.

Conclusion: The high rate of recurrence detection by PSMA PET was confirmed and PSMA PET led to a change in management in 60% of patients. Focal therapy for PSMA-positive lesions is a promising approach with complete responses in 45% of patients.

Keywords: Biochemical recurrence; Change in management; Detection rate; PSMA; Prostate cancer; Targeted.