11C-acetate PET/CT before radical prostatectomy: nodal staging and treatment failure prediction

Despite early detection programs, many patients with prostate cancer present with intermediate- or high-risk disease. We prospectively investigated whether (11)C-acetate PET/CT predicts lymph node (LN) metastasis and treatment failure in men for whom radical prostatectomy is planned.

Methods: 107 men with intermediate- or high-risk localized prostate cancer and negative conventional imaging findings underwent PET/CT with (11)C-acetate. Five underwent LN staging only, and 102 underwent LN staging and prostatectomy. PET/CT findings were correlated with pathologic nodal status. Treatment-failure-free survival was estimated by the Kaplan-Meier method. The ability of PET/CT to predict outcomes was evaluated by multivariate Cox proportional hazards analysis.

Results: PET/CT was positive for pelvic LN or distant metastasis in 36 of 107 patients (33.6%). LN metastasis was present histopathologically in 25 (23.4%). The sensitivity, specificity, and positive and negative predictive values of PET/CT for detecting LN metastasis were 68.0%, 78.1%, 48.6%, and 88.9%, respectively. Treatment failed in 64 patients: 25 with metastasis, 17 with a persistent postprostatectomy prostate-specific antigen level greater than 0.20 ng/mL, and 22 with biochemical recurrence (prostate-specific antigen level > 0.20 ng/mL after nadir) during follow-up for a median of 44.0 mo. Treatment-failure-free survival was worse in PET-positive than in PET-negative patients (P < 0.0001) and in those with false-positive than in those with true-negative scan results (P < 0.01), suggesting that PET may have demonstrated nodal disease not removed surgically or identified pathologically. PET positivity independently predicted failure in preoperative (hazard ratio, 3.26; P < 0.0001) and postoperative (hazard ratio, 3.07; P = 0.0001) multivariate models.

Conclusion: In patients planned for or completing prostatectomy, (11)C-acetate PET/CT detects LN metastasis not identified by conventional imaging and independently predicts treatment-failure-free survival.