Impact of 18F-fluciclovine PET on salvage radiotherapy plans for men with post-radical prostatectomy recurrence of prostate cancer.

Abstract

19 Background: Imaging options to localize lesions in men with biochemical recurrence (BCR) of prostate cancer after radical prostatectomy (RP) are limited, especially at low PSA levels. Consequently, radiation oncologists typically target the prostate bed (PB) with or without pelvic lymph nodes (LN) based on clinical or pathologic features. The FALCON study (NCT02578940) evaluated the clinical benefit of 18F-fluciclovine PET through its impact on management plans for men with BCR. Here, we report the impact on salvage radiotherapy (RT) decisions in men post-RP. Methods: Men with a first BCR episode following curative-intent therapy who were being considered for salvage therapy underwent 18F-fluciclovine PET at one of 6 UK sites. Physicians documented patients’ treatment plans pre- and post-scan. Imaging results and management plans were stratified by prior treatment as determined from patient records. Results: Sixty-five (63%) of the 104 FALCON patients had undergone RP. Of these, 62 (median PSA, 0.32 ng/mL) had a pre-scan plan for salvage RT. Lesions were found in 21 (34%) patients (median PSA, 0.32 ng/mL), of whom 10 (16%; median PSA, 0.54 ng/mL) had extraprostatic findings (Table). Post-scan, 25 (40%) men had a management change, 17 (68%) due to a positive scan. Of the 25 post-scan revisions, 17 (68%) were changes to the treatment modality: 8 to systemic therapy, 8 to watchful waiting, 1 other. A further 8 (32%) men had RT fields modified: PB alone modified to include a boost to a 18F-fluciclovine-avid lesion (n = 7) or whole pelvis field refocused on a smaller area (n = 1). Conclusions: Two fifths of men scheduled to undergo salvage RT after RP had their management plan revised following 18F-fluciclovine PET. The majority of changes involved a completely new treatment modality. Future studies to evaluate the clinical outcomes of such changes are warranted. Clinical trial information: NCT02578940. [Table: see text]