Presentation Authors: Julio Chong*, Mitchel Muhleman, Rollin Say, Lale Kostakoglu, Jalal Ahmed, Ashutosh Tewari, Richard Stock, William Oh, New York, NY
Introduction: Positron emission tomography/computed tomography (PET/CT) with 18F-fluciclovine can improve the detection of recurrent prostate cancer (PCa). We assessed for factors which may increase detection, evaluated the ability of 18F-fluciclovine to alter treatment, and identified an optimal PSA cut-off to screen for recurrent disease.
Methods: Patients who received 18F-fluciclovine for post-treatment recurrent PCa were analyzed to compare clinical features between patients with positive vs. negative scans. Treatment changes were tracked. A receiver-operator characteristic (ROC) curve was used to estimate the optimal PSA cut-off to predict for a positive scan.
Results: 78 patients with post-treatment recurrent PCa received 18F-fluciclovine PET/CT. 18F-fluciclovine predicted radiographic recurrence in 67.9% of patients. Age, time from diagnosis to scan, PSA at diagnosis, Gleason grade, treatment type, nadir PSA, and PSA velocity were similar between groups. PSA at scan (p = 0.010), salvage therapy (p = 0.03), any use of ADT (p = 0.016), and mean number of scans since rising PSA (p = 0.042) were all associated with a positive scan (Table 1). Alteration of treatment plans occurred in 34/58 (58.6%) patients. Recurrence sites are: 79/120 (65.8%) lymph nodes, 27/120 (22.5%) bone, 11/120 (9.2%) prostatic bed, and 3/120 (2.5%) elsewhere. The most common treatment alterations were directed stereotactic body radiation therapy (SBRT) (16/34, 47%), salvage surgical resection (4/34, 11.7%), and continuous ADT (3/34, 8.7%). Eleven of 34 (32.3%) patients with positive scans were referred to start SBRT. The optimal PSA cut-off based on ROC curve was 0.5 with sensitivity of 81.13% and specificity of 78.38% (Figure 1).
Conclusions: 18F-fluciclovine PET/CT detected recurrence in 67.9% of patients, resulting in alteration in treatment plans in 58.6% of cases. SBRT was the most common alteration in treatment plan. Previous use of salvage therapy or ADT are risk factors, and when combined with a PSAâ‰¥0.5 may predict radiographic recurrence.