Early outcome prediction on 18F-fluorocholine PET/CT in metastatic castration-resistant prostate cancer patients treated with abiraterone

// Ugo De Giorgi 1 , Paola Caroli 2 , Salvatore L. Burgio 1 , Cecilia Menna 1 , Vincenza Conteduca 1 , Emanuela Bianchi 1 , Francesca Fabbri 3 , Elisa Carretta 3 , Dino Amadori 1 , Giovanni Paganelli 2 , Federica Matteucci 2 1 Department of Medical Oncology, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (I.R.S.T.) IRCCS, Meldola, Italy 2 Department of Nuclear Medicine, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (I.R.S.T.) IRCCS, Meldola, Italy 3 Biostatistics and Clinical Trials Unit, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (I.R.S.T.) IRCCS, Meldola, Italy Correspondence to: Ugo De Giorgi, e-mail: ugo.degiorgi@irst.emr.it Keywords: Abiraterone, Castration-resistant prostate cancer, 18F-fluorocholine positron emission tomography, PSA, Bone flare Received: August 13, 2014      Accepted: October 01, 2014      Published: October 11, 2014 ABSTRACT Objective: We investigated the role of 18F-fluorocholine positron emission tomography/computed tomography (FCH-PET/CT) in the early evaluation of abiraterone and outcome prediction in patients with metastatic castration-resistant prostate cancer (CRPC). Patient and methods: Forty-three patients with metastatic CRPC progressing after docetaxel received abiraterone 1,000 mg daily with prednisone 5 mg twice daily. Patients were evaluated monthly for serological PSA response and safety. FCH-PET/CT was done at baseline and after 3 to 6 weeks. Univariate and multivariate Cox regression models addressed potential predictors of progression-free survival (PFS) and overall survival (OS). Results: Declines in PSA level of ≥50% were seen in 21 of 43 (49%) patients. Forty-two patients were evaluable for FCH-PET/CT response. FCH-PET/CT bone flare was observed in 4 of 42 (10%) evaluable patients. In univariate analysis, PSA decline and FCH-PET/CT response predicted PFS, while PSA decline and FCH-PET/CT (progression vs non progression) predicted OS. In multivariate analysis, only FCH-PET/CT (progression vs nonprogression) remained significant for PFS and OS ( p = 0.022 and p = 0.027, respectively). Conclusion: Early FCH-PET/CT can predict clinical outcome in CRPC beyond PSA response. These data support further studies on FCH-PET/CT for abiraterone monitoring and outcome prediction in patients with CRPC.