Oligometastatic Prostate Cancer Treated with Metastasis-Directed Therapy Guided by Positron Emission Tomography: Does the Tracer Matter?

Abstract

The superior diagnostic accuracy of [68Ga]Ga-prostate-specific membrane antigen-11 (PSMA) ([68Ga]Ga-PSMA-11) compared to [18F]F-Fluorocholine Positron Emission Tomography/Computed Tomography (PET/CT) in Prostate Cancer (PCa) is established. However, it is currently unclear if the added diagnostic accuracy actually translates into improved clinical outcomes in oligometastatic PCa patients treated with [68Ga]Ga-PSMA-11 PET-guided metastasis-directed therapy (MDT). The present study aimed to assess the impact of these two imaging techniques on Progression-Free Survival (PFS) in a real-world sample of oligometastatic PCa patients submitted to PET-guided MDT. Thirty-seven oligometastatic PCa patients treated with PET-guided MDT were retrospectively enrolled. MDT was guided by [18F]F-Fluorocholine PET/CT in eleven patients and by [68Ga]Ga-PSMA-11 PET/CT in twenty-six. Progression was defined as biochemical recurrence (BR), radiological progression at subsequent PET/CT imaging, clinical progression, androgen deprivation therapy initiation, or death. Clinical and imaging parameters were assessed as predictors of PFS. [18F]F-Fluorocholine PET-guided MDT was associated with significantly lower PFS compared to the [68Ga]Ga-PSMA-11 group (median PFS, mPFS 15.47 months, 95% CI: 4.13–38.00 vs. 40.93 months, 95% CI: 40.93–40.93, respectively; p < 0.05). Coherently, the radiotracer used for PET-guided MDT resulted in predictive PFS at the univariate analysis, as well as the castration-resistant status at the time of MDT and the PSA nadir after MDT. However, in the multivariate analysis, castration resistance and PSA nadir after MDT remained the sole independent predictors of PFS. In conclusion, in the present proof-of-concept study, [68Ga]Ga-PSMA-11 provided higher PFS rates than [18F]F-Fluorocholine imaging in oligometastatic PCa patients receiving PET-guided MDT. Although preliminary, this finding suggests that enlarging the “tip of the iceberg”, by detecting a major proportion of the submerged disease thanks to next-generation imaging may favourably impact the oncological outcome of oligometastatic PCa treated with MDT.

Diverse Imaging Methods May Influence Long-Term Oncologic Outcomes in Oligorecurrent Prostate Cancer Patients Treated with Metastasis-Directed Therapy (the PRECISE-MDT Study)

“…There is considerable uncertainty in interpreting and applying clinical trial findings for oligorecurrent PCa, mainly attributable to varied imaging approaches. Table 4 summarizes existing realworld retrospective studies (13)(14)(15)(16)(17) comparing the efficacy of different imaging-guided MDT approaches. Beyond providing a larger patient sample, our multiinstitutional observational study contributes additional valuable insights.…”

Predictive value of volumetric parameters based on 18F-PSMA-1007 PET/CT for prostate cancer metastasis

“…At present, the definition of oligometastatic PCa has not been clearly established, particularly concerning the extent and distribution of metastatic lesions. However, a majority of studies have established a threshold of 3-5 metastatic sites on conventional imaging as the delineating criterion ( 10 ). Further studies have shown that the management of primary and metastatic lesions in individuals diagnosed with oligometastatic PCa tends to enhance both their quality of life and overall survival ( 11 , 12 ).…”