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 To address the impact of preoperative PSMA PET (prostate specific membrane antigen positron emission tomography) findings prior to radical prostatectomy (RP) and pelvic lymph node dissection (PLND) on biochemical recurrence (BCR) and time to adjuvant or salvage treatment. MATERIALS AND METHODS Between 2013 and 2017, 64 intermediate- and 166 high-risk (n=230) prostate cancer (PCa) patients received 68Ga-PSMA-11 PET followed by RP and PLND. BCR-free and therapy-free survival was determined. For all time to event analyses, uni- and multivariable Cox's 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 follow up was 30.2 months. BCR occurred in 50.4% (n=116) of patients and adjuvant or salvage treatment was performed in 46.5% (n=107). Worst BCR-free and therapy-free survival was observed in pN1 patients who also exhibited PSMA PET positive LN, followed by pN1 patients without PSMA PET positive LN and patients without evidence of LN metastasis on histology and PSMA PET (median BCR-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 LN on PSMA PET prior to RP have to expect early BCR and adjuvant/salvage therapy, despite thorough PLND. Therefore, results from PSMA PET can be used for patients' consultation, more stringent follow-up as well as for planning of neo-/adjuvant therapy.