68Ga-prostate-specific membrane antigen (PSMA) PET/CT as a clinical decision-making tool in biochemically recurrent prostate cancer after definitive treatment: An Australian prospective study.

Aims: Prostate-specific membrane antigen (PSMA) PET/CT has emerged as the optimal imaging modality to detect recurrent prostate cancer in patients with biochemical relapse (BCR) following curative intent treatment. However, its impact on clinical decision making in the era of metastasis-directed therapy remains unclear. This study aims to explore the role of PSMA PET/CT on clinical decisionmaking in patients with BCR following definitive therapy. Method(s): We prospectively enrolled 40 patients with BCR to undergo 68Ga-PSMA PET/CT. Baseline clinicopathological factors were obtained and referring clinicians documented their proposed treatment plan both prior to and following imaging. Changes in clinical management were considered to have clinical impact. Result(s): 68Ga-PSMA PET/CT detected at least one suspicious lesion in 23/40 (58%) patients, with a median PSA level of 0.59 mug/L (IQR 0.21- 2.31). Positive scansweremore frequent at higher PSA levels (P<.001, Fischer's exact test). The most common sites of PSMA-avid disease were lymph nodes (61%) and bone (30%). Lymph node involvement was typically pelvic nodes (13/14, 93%). Bone involvement was mostly outside the axial skeleton (5/7, 71%). PSMA PET/CT altered management in 21/40 (53%) patients. Of those planned for watchful waiting, 14/24 (58%) proceeded to amore activemanagement strategy, including salvage radiotherapy (n = 6), stereotactic ablative body radiotherapy (SABR; n = 5), androgen deprivation therapy (n = 2) and salvage surgery (n = 1). Conclusion(s): 68Ga-PSMA PET/CT altered management strategy in a significant proportion of prostate cancer patients with BCR following definitive therapy. Our data demonstrate a shift from planned watchful waiting to more active treatment in over half patients with a positive 68Ga-PSMA PET/CT. Longer-term follow-up is required to assess the influence of such strategies on clinical outcomes.