Utility of anti-3-[18F] FACBC PET/CT to predict early biochemical failure following salvage cryotherapy for recurrent prostate cancer

345 Objectives anti-3-[18F] FACBC is a synthetic amino acid PET radiotracer with utility in the detection of recurrent prostate carcinoma (Radiology 2011;259:852). We explore the utility of FACBC PET in predicting early PSA failure in patients who underwent salvage cryotherapy for recurrent prostate cancer. Methods 25 patients with biopsy proven recurrent prostate carcinoma underwent salvage cryotherapy after dual time point (4 and 17 min) FACBC PET. Early PSA failure was defined as PSA at 6 months post-cryotherapy greater than nadir PSA post-cryotherapy plus 2 ng/ml. We then compared the following factors between failure and non-failure groups: FACBC lesion SUVmax and target to background (TBR) ratios at 4 and 17 min, tracer retention index (RI), original Gleason score, pre-salvage PSA, and focal vs heterogeneous prostate FACBC tracer distribution. Results were analyzed using a combination of T test, ANOVA, and multivariate analysis. Significance was set at p Results 8/25 (32%) patients had early PSA failure. The failure vs non-failure group had higher mean (± SD) SUVmax at 4min (7.2±2.3 vs 5.8±1.9) and 17 min (6.0±2.4 vs 4.1±1.2), but was statistically significant only at 17 min (p=0.01). The failure vs non-failure group also had a significantly higher pre-salvage PSA (9.5±4.9 vs 5.5±3.9; p=0.03). There was no significant correlation between pre-salvage PSA and SUV max. Neither TBR, RI, Gleason score, pattern of tracer uptake were significantly different between the groups. On multivariate analysis, no independent predictor of failure was found. Conclusions FACBC SUV max at 17 min and pre-salvage PSA levels were significantly higher in salvage cryotherapy early failure vs non-failure groups, and may help predict patients at risk for early post-salvage cryotherapy failure. Research Support NIH (1 R01 CA 129356-01) and Georgia Cancer Coalition