Robotic Salvage Lymph Node Dissection in Recurrent Prostate Cancer: Lessons Learned from 68 Cases and Implications for Future Clinical Management.

PURPOSE: Salvage lymph node dissection is a rescue treatment for patients with nodal recurrence after radical prostatectomy. Very limited data are available on robotic salvage lymph node dissection. Our purpose was to investigate perioperative and oncological outcomes of robotic salvage lymph node dissection in a large monocentric series. MATERIALS AND METHODS: Perioperative data, complications within 30 days after surgery and oncological outcomes as assessed by histology, prostate specific antigen changes, prostate specific antigen nadir after salvage lymph node dissection, and time to further therapy were analyzed. To identify predictive factors for oncological outcome, Kaplan-Meier and Cox-regression analyses were performed. For cases with a mismatch between preoperative positron emission tomography/computed tomography and the number of histologically positive lymph nodes, prostate specific membrane antigen immunohistochemistry was performed on removed lymph nodes. RESULTS: A total of 68 patients underwent robotic salvage lymph node dissection with a median operation time of 126 minutes, a blood loss of 50 ml, and a length of stay of 4 days. No major complications (>Clavien 3) occurred. Median followup was 12.1 months. Median time to further therapy was 12.4 months, 37% of patients experienced complete biochemical response (prostate specific antigen <0.2 ng/ml) and 11% reached an undetectable prostate specific antigen, which was maintained for >1 year in 3 cases. Lower preoperative prostate specific antigen, longer time between radical prostatectomy and salvage lymph node dissection, preoperative prostate specific membrane antigen positron emission tomography/computed tomography and complete biochemical response after salvage lymph node dissection were significant predictors of longer therapy-free survival (all p <0.005). Prostate specific membrane antigen immunohistochemistry revealed that prostate specific membrane antigen positron emission tomography/computed tomography tends to miss small lymph node metastases <5 mm. CONCLUSIONS: Robotic salvage lymph node dissection is a feasible approach with low perioperative morbidity and delays further systemic therapy in most patients. Prostate specific membrane antigen positron emission tomography/computed tomography detection is mostly limited to tumor foci >5 mm.

Patient-derived, three-dimensional spheroid cultures provide a versatile translational model for the study of organ-confined prostate cancer.

PURPOSE: To generate and characterize 3D spheroid suspension cultures from radical prostatectomy (RP) specimens as a versatile model system for organ-confined prostate cancer (PCa). METHODS: Cancerous tissue samples from RP specimens were excised by a uropathologist. Preparation of 3D spheroids was done by mechanical disintegration and limited enzymatic digestion followed by serial filtration through 100 µm- and 40 µm-cell strainers. Thereafter, spheroids were cultured in a modified stem cell medium and characterized by a live/dead assay, whole-spheroid immunohistochemistry (IHC; CK5, CK8, AMACR, PSA, Ki67, AR, αSMA, Vimentin, E-Cadherin) and PSA-measurements in culture medium. Furthermore, their response to pharmaceutical treatment with docetaxel, bicalutamide, enzalutamide and abiraterone was tested. RESULTS: 173 RP cases were included. The median preoperative PSA-level was 16.12 ng/ml [range 0.99;345], the median Gleason score was 7b [6;10]. 64 cases were excluded due to low tumor content in frozen sections (43) or to insufficient spheroid formation (21). In the remaining 109 cases, spheroids formed successfully and stayed viable for up to several months. IHC analysis revealed AR-, CK8-, and AMACR-positivity in nearly all cases, while CK5-positive cells were detectable only occasionally as were α-SMA and Vimentin. E-Cadherin was positive in most cases. Furthermore, spheroids proved to be amenable to cryopreservation. While abiraterone had no effect and docetaxel only a moderate effect, spheroid viability was markedly reduced upon bicalutamide and enzalutamide treatment. CONCLUSIONS: Multicellular 3D spheroids can be generated from patient-derived RP tissue samples and serve as an innovative in vitro model of organ-confined PCa.