11C-choline PET/CT predicts survival in prostate cancer patients with PSA < 1 NG/ml

Purpose: The main drawback of 11C-choline PET/CT for restaging prostate cancer (PCa) patients with biochemical failure is the relatively low positive detection rate for prostate specific antigen (PSA) < 1 ng/ml. This study assessed whether 11C-choline PET/CT predicts survival in PCa patients with PSA < 1 ng/ml. Methods: This retrospective study included 210 PCa patients treated with radical prostatectomy who underwent 11C-choline PET/CT from December 1, 2004 to July 31, 2007 due to biochemical failure. PCa-specific survival was estimated using Kaplan–Meier curves. Cox regression analysis was used to evaluate the association between clinicopathologic variables and PCa-specific survival. PCa-specific survival was computed as the interval from radical prostatectomy to PCa-specific death. Results: Median follow-up after radical prostatectomy was 6.9 years (95% confidence interval, CI, 2.0–14.5 years). 11C-choline PET/CT was positive in 20.5% of patients. Median PCa-specific survival was 13.4 years (95% CI, 9.9–16.8 years) in patients with positive 11C-choline PET/CT, and it was not achieved in patients with negative 11C-choline PET/CT (log-rank, chi-square = 15.0, P < 0.001). Ten-year survival probabilities for patients with negative 11C-choline PET/CT and for patients with positive 11C-choline PET/CT were 86.0% (95% CI: 80.7%–91.3%) and 63.6% (95% CI: 54.5–72.7%). At multivariate analysis, only 11C-choline PET/CT significantly predicted PCa-specific survival (hazard ratio = 2.54, 95% CI, 1.05–6.13, P = 0.038). Patients with pathological 11C-choline uptake in the prostatic bed or in pelvic lymph nodes had longer PCa-specific survival in comparison to patients with pathological tracer uptake in the skeleton (log-rank: chi-square = 27.4, P < 0.001). Conclusion: Despite the relatively low positive detection rate for PSA < 1 ng/ml, positive 11C-choline PET/CT predicts PCa-specific survival in this low PSA range. As long as more sensitive radiotracers, such as 68Ga-PSMA-11, do not become more widely available, these results might support a broader use of radiolabeled choline in restaging PCa for PSA < 1 ng/ml.