The Optimal Timing for PSMA PET/CT in Patients with Biochemical Recurrence After Radical Prostatectomy
Menée à partir de données portant sur 419 patients atteints d'un cancer de la prostate ayant récidivé biochimiquement après une prostatectomie radicale (niveau du PSA inférieur à 2.0 ng/ml), cette étude évalue la performance d'un modèle, basé sur des variables clinico-pathologiques (niveau du PSA au moment de l'examen d'imagerie, grade et stade de la tumeur, statut des marges de résection), pour prédire le risque de détecter une récidive en dehors de la fosse prostatique et déterminer ainsi à quel moment réaliser une tomographie numérique à émission de positrons à base du traceur "68Ga-PSMA-11"
Purpose: To develop a model predicting the probability of detecting prostate cancer (PCa) recurrence outside the prostatic fossa on PSMA PET/CT in patients with biochemical recurrence (BCR) after radical prostatectomy (RP).
Materials and Methods: We retrospectively included 419 consecutive patients with BCR (PSA<2.0 ng/ml) after RP who underwent 68Ga-PSMA-11 PET/CT to guide salvage therapy. Patients receiving androgen deprivation therapy between RP and PSMA PET/CT were excluded. We used multivariable logistic regression to assess predictors for the detection of PCa recurrence outside the prostatic fossa on PSMA PET/CT. We minimalized overfitting of the model and used decision curve analysis (DCA) to determine clinical utility.
Results: Median PSA at time of scanning was 0.40 (interquartile range 0.30-0.70) ng/ml. 174 (42%) patients had PCa recurrence outside the prostatic fossa. PSA at time of scanning, and grade group, N-stage and surgical margin status at RP specimen were significant predictors for detecting PCa recurrence outside the prostatic fossa. The bootstrapped AUC of this model was 0.75 (interquartile range 0.73–0.77). The DCA showed a net benefit by a model-based probability from 16%. Limitations include the retrospective design and the missing histological correlation of positive lesions.
Conclusions: Next to the PSA value at time of scanning, grade group, N-stage and surgical margin status at RP specimen are significant predictors for detecting PCa recurrence outside the prostatic fossa on PSMA PET/CT. The presented model is implemented in a dashboard to assist clinicians in determining the optimal moment to perform 68Ga-PSMA PET/CT in patients with BCR after RP.
Journal of Urology , résumé, 2019