Regional Lymph Node Metastasis on Prostate Specific Membrane Antigen Positron Emission Tomography Correlates with Decreased Biochemical Recurrence-Free and Therapy-Free Survival after Radical Prostatectomy: A Retrospective Single-Center Single-Arm Observational Study

PURPOSE: We sought to address the impact of preoperative prostate specific membrane antigen (PSMA) positron emission tomography (PET) findings prior to radical prostatectomy and pelvic lymph node dissection on biochemical recurrence and time to adjuvant or salvage treatment.

MATERIALS AND METHODS: Between 2013 and 2017, 64 intermediate and 166 high risk (230) prostate cancer patients received 68Ga-PSMA-11 PET followed by radical prostatectomy and pelvic lymph node dissection. Biochemical recurrence-free and therapy-free survivalwere determined. For all time-to-event analyses, univariable and multivariable Cox proportional hazards models and univariable Kaplan-Meier analyses were applied, with a significance threshold of p <0.05.

RESULTS: The overall sensitivity, specificity, positive predictive value and negative predictive value of PSMA PET for pN1 disease was 48.5%, 95.7%, 82.1% and 82.2%, respectively. Median followup was 30.2 months. Biochemical recurrence occurred in 50.4% (116) of patients and adjuvant or salvage treatment was performed in 46.5% (107). Worst biochemical recurrence-free and therapy-free survival was observed in pN1 patients who also exhibited PSMA PET positive lymph node, followed by pN1 patients without PSMA PET positive lymph node and patients without evidence of lymph node metastasis on histology and PSMA PET (median biochemical recurrence-free survival 1.7 vs. 7.5 vs. >36 months, median therapy-free survival 2.6 vs. 8.9 vs. >36 months).

CONCLUSIONS: Patients with positive lymph node on PSMA PET prior to radical prostatectomy have to expect early biochemical recurrence and adjuvant/salvage therapy, despite thorough pelvic lymph node dissection. Therefore, results from PSMA PET can be used for patients' consultation and more stringent followup as well as for planning of neoadjuvant/adjuvant therapy.