Use of 18F-fluciclovine PET/CT (FluPET) for prostate cancer (PC): Initial results from a prospective registry at a tertiary academic center.

Abstract

29 Background: FluPET, a next-generation imaging modality approved in 2016 for suspected PC recurrence with elevated PSA after prior therapy, is becoming more widely available; however, practice patterns and impact on outcomes is unknown. We hypothesize FluPET is ordered for a variety of reasons, with findings often leading to changes in treatment plan. Methods: In this prospective registry, providers are surveyed before, 1-2 weeks after, and 1 year after FluPET to assess reasons for obtaining FluPET, projected treatment plan, changes in plan due to FluPET findings, and toxicity potentially attributable to change in treatment plan. Baseline patient characteristics, FluPET results, and longitudinal outcomes are collected. We report early descriptive findings with χ2 and student’s t-test used for univariate analyses. Results: 50 patients enrolled 12/2018-08/2020 had baseline characteristics described in Table; 46 underwent FluPET. Rationale for ordering included initial staging prior to definitive local therapy (6.1%), guidance of salvage local therapy for 1st biochemical recurrence (BCR) (46.9%), guidance of additional salvage after ≥2 local therapies and 2nd BCR (36.7%), and confirmation of equivocal metastatic disease (10.2%). When queried on next steps, providers considered observation (67.3%), androgen deprivation therapy (ADT) (26.5%), ADT + docetaxel or novel anti-androgens (AA) (20.4%), and salvage therapy with surgery, radiation, or cryotherapy (26.5%), often selecting ≥1 option. FluPET found ≥1 PC lesion in 73.9% of cases, ≥1 indeterminate lesion in 8.7%, and no lesions in 17.4%. 45.5% of providers reported changing treatment plan based on FluPET results; 6.8% changed to observation, 20.5% to systemic therapy, 13.6% to local salvage therapy, and 4.5% to a combination of local and systemic therapies. Change in therapy was associated with positive FluPET (54.5% vs. 18.2%, p=0.044), and within those cases, with higher SUVMax (mean 7.7 vs. 5.2, p=0.021) but not number of lesions (p=0.804). Conclusions: FluPET is often obtained to guide salvage therapy after BCR but is also used for initial staging or resolving equivocal findings of metastases. Many providers changed intended treatment based on FluPET findings, especially if positive; de-escalation to observation was rare. [Table: see text]