Management Impact of Metachronous Oligometastatic Disease Identified on 18F-Fluciclovine (Axumin™) PET/CT in Biochemically Recurrent Prostate Cancer.

Abstract

We assessed the incidence rate and management impact of oligometastatic disease detected on 18F-fluciclovine (Axumin™) PET/CT in men with first biochemical recurrence (BCR) of prostate cancer (PCA) after definitive primary therapy. We retrospectively reviewed our clinical database for men with PCA who underwent 18F-fluciclovine PET/CT for imaging evaluation of BCR with negative or equivocal findings on conventional imaging. We included patients with up to and including 5 metastases (oligometastases) regardless of imaging evidence for local recurrence in the treated prostate bed. We examined the association between mean serum prostate specific antigen (PSA) levels with the number of oligometastases (non-parametric ANOVA) and between patients with or without local recurrence (Student t-test). The management impact of oligometastatic disease was tabulated. We identified 21 patients with oligometastases upon first BCR (PSA 0.2-56.8ng/mL) out of 89 eligible patients. There was a significant difference (p = 0.04) in the mean PSA levels between patients with local recurrence (n = 12) and those without local recurrence (n = 9). In the subgroup of analysis of patients without local recurrence, there was no significant association between mean PSA level and number of oligometastases (p = 0.83). Distribution of oligometastases included 66.7% isolated nodal disease and 33.3% bone only. Twelve (57.1%) patients had change in management to include change in ADT, salvage therapy, or both. Treatment change was initiated in 62.5%, 28.6%, 66.7%, 100%, and 100% of patients with 1, 2, 3, 4, and 5 oligometastatic lesions, respectively. The incidence rate of oligometastatic disease in men with first BCR of PCA undergoing 18F-fluciclovine PET/CT for imaging evaluation of BCR was 23.6% in our eligible patient population. There was no significant association between serum PSA level and the number of oligometastases. Treatment management was affected in 57.1% of patients with oligometastases.