Sentinel Lymph Node Biopsy in Prostate Cancer: An Overview of Diagnostic Performance, Oncological Outcomes, Safety, and Feasibility

Sentinel node biopsy (SNB) for prostate cancer (PCa) represents an innovative technique aimed at improving nodal staging accuracy. The routinary adoption of this procedure in patients undergoing radical prostatectomy (RP) might be crucial to identify candidates who could effectively benefit from extensive pelvic lymph nodal dissection (ePLND). Despite some promising results, SNB for PCa is still considered experimental due to the lack of solid evidence and procedural standardization. In this regard, our narrative review aimed to analyze the most recent literature in this field, providing an overview of both the diagnostic accuracy measures and the oncological outcomes of SNB.

A hybrid radioactive and fluorescence approach is more than the sum of its parts; outcome of a phase II randomized sentinel node trial in prostate cancer patients

OBJECTIVE

To determine the diagnostic accuracy of the hybrid tracer indocyanine green (ICG)-Technetium-99 m(99mTc)-nanocolloid compared to sequential tracers of 99mTc-nanocolloid and free-ICG in detecting tumor-positive lymph nodes (LN) during primary surgery in prostate cancer (PCa) patients.

INTRODUCTION

Image-guided surgery strategies can help visualize individual lymphatic drainage patterns and sentinel lymph nodes (SLNs) in PCa patients. For lymphatic mapping radioactive, fluorescent and hybrid tracers are being clinically exploited. In this prospective randomized phase II trial, we made a head-to-head comparison between ICG-99mTc-nanocolloid (hybrid group) and 99mTc-nanocolloid and subsequent free-ICG injection (sequential group).

METHODS

PCa patients with a  >5% risk of lymphatic involvement according to the 2012 Briganti nomogram and planned for prostatectomy were included and randomized (1:1) between ultrasound-guided intraprostatic tracer administration of ICG-99mTc-nanocolloid (n = 69) or 99mTc-nanocolloid (n = 69) 5 h before surgery. Preoperative lymphoscintigraphy and SPECT/CT were performed to define the locations of the SLNs. Additionally, all participants in the sequential group received an injection of free-ICG at time of surgery. Subsequently, all (S)LNs were dissected using fluorescence guidance followed by an extended pelvic lymph node dissection (ePLND). The primary outcome was the total number of surgically removed (S)LNs and tumor-positive (S)LNs.

RESULTS

The total number of surgically removed (S)LN packages was 701 and 733 in the hybrid and sequential groups, respectively (p = 0.727). The total number of fluorescent LNs retrieved was 310 and 665 nodes in the hybrid and sequential groups, respectively (p < 0.001). However, no statistically significant difference was observed in the corresponding number of tumor-positive nodes among the groups (44 vs. 33; p = 0.470). Consequently, the rate of tumor-positive fluorescent LNs was higher in the hybrid group (7.4%) compared to the sequential group (2.6%; p = 0.002), indicating an enhanced positive predictive value for the hybrid approach. There was no difference in complications within 90 days after surgery (p = 0.78).

CONCLUSIONS

The hybrid tracer ICG-99mTc-nanocolloid improved the positive predictive value for tumor-bearing LNs while minimizing the number of fluorescent nodes compared to the sequential tracer approach. Consequently, the hybrid tracer ICG-99mTc-nanocolloid enables the most reliable and minimal invasive method for LN staging in PCa patients.

Indocyanine green guidance improves the efficiency of extended pelvic lymph node dissection during laparoscopic radical prostatectomy

OBJECTIVES

To evaluate whether indocyanine green guidance can improve the quality of extended pelvic lymph node dissection in patients undergoing radical prostatectomy.

METHODS

A total of 214 patients underwent laparoscopic radical prostatectomy with indocyanine green-guided lymph node dissection plus extended pelvic lymph node dissection. These patients (group A) were matched 1:1 for clinical risk groups according to the National Comprehensive Cancer Network classification with patients who underwent the same procedure without fluorescence guidance (group B). Biochemical recurrence was defined as two consecutive prostate-specific antigen rises of at least 0.2 ng/mL. The Kaplan-Meier method and Cox regression models were used to identify predictors of biochemical recurrence.

RESULTS

The median number of retrieved nodes was significantly higher in group A (22 vs 14, P < 0.001). The rate of lymph node metastases was higher in group A (65.9% vs 34.1%, P = 0.01). Increasing the yield of lymph node dissection was independently and negatively correlated with the biochemical recurrence risk in both overall and pN-positive patients (hazard ratio 0.97, P = 0.03; and hazard ratio 0.95, P = 0.02). The 5-year biochemical recurrence-free survival rates were (75.8% vs 65.9, P = 0.09) and (54.1% vs 24.9%, P = 0.023) for group A and group B in the overall cohort and pN-positive cohort, respectively.

CONCLUSION

Indocyanine green-guided lymph node dissection plus extended pelvic lymph node dissection improves identification of lymphatic drainage, resulting in a higher number of lymph nodes and retrieved lymph node metastases, and allowing a more accurate local staging and a prolonged biochemical recurrence-free survival.

Prostate-specific antigen associates with extensive lymph node invasion in high-risk prostate cancer

OBJECTIVE

To evaluate clinical predictors of lymph node invasion (LNI) in patients with high-risk prostate cancer undergoing radical prostatectomy (RP) with extended pelvic lymph node dissection (ePLND).

METHODS

A contemporary cohort of 116 patients, who underwent ePLND during RP, was retrospectively evaluated. Patients were classified into 3 groups including cases without LNI (group 1), with 1 to 3 positive nodes (group 2; limited LNI), and with more than 3 positive nodes (group 3; extensive LNI). The multinomial logistic regression model (multivariate analysis) evaluated the risk of LNI.

RESULTS

Overall, 30 patients (25.9%) had LNI, which was limited in 17 cases (14.7%) and extensive in 13 subjects (11.2%). Median prostate-specific antigen (PSA) was higher in cases with limited (11.4 ng/mL) or extensive (23.5 ng/mL) LNI than cases without (7.3 ng/mL) and the difference was significant ( p <.0001). Median proportion of biopsy-positive cores was higher in limited (0.64) or extensive (0.54) LNI than cases without (0.34) and the difference was significant ( p < .0001). The distribution of other factors did not show any significant difference among the groups. On multivariate analysis, only higher values of PSA significantly affected the odds of extensive LNI when compared to cases without (odds ratio, 1.054; p = .005); PSA showed a fair discrimination power (area under the curve 0.792).

CONCLUSION

PSA was the only independent predictor of extensive LNI and could be an important preoperative factor for stratifying high-risk patients.

[Long-term outcomes of prostate cancer patients with lymph nodes metastasis after radical prostatectomy and pelvic lymph node dissection]

INTRODUCTION

The aim of this study was to evaluate biochemical recurrence-free survival (RFS) and to identify useful predictors of such survival in localized prostate cancer patients (cN0) and pelvic lymph node metastasis (pN+) treated with radical prostatectomy and pelvic lymph node dissection.

PATIENTS AND METHODS

This multicenter and retrospective study, assessed overall survival (OS), cancer specific survival (CSS) and biochemical recurrence-free survival (RFS), between January 2005 until December 2010 with 5 years of distance. We evaluated factors predicting long-term RFS in node positive prostate cancer patients.

RESULTS

Thus, 30 patients were included. Median follow-up was 89.9±27.4 months. After surgery, patients were treated with surveillance (n=4, 13.5%), adjuvant hormone therapy (n=22, 73%) or combination of radio and hormone therapy, (n=4, 13.5%). During the follow-up, 50% of patients had biochemical recurrence, with a mean time period of 38±30 months. Five and 10-year RFS were 57% and 41% respectively. Extra lymph nodes extension (P=0.00021) and pathological margin status (P=0.0065) were independent predictors of 5-year RFS.

CONCLUSION

Biochemical RFS of patients treated with radical prostatectomy and subclinical lymph node metastatic disease is adequate and multifactorial. However, this study identifies pathological margin status and extra lymph node extension as independent factors of b RFS.

LEVEL OF EVIDENCE

4.

Current technique and results for extended pelvic lymph node dissection during robot-assisted radical prostatectomy

The practice of extended pelvic lymph node dissection (ePLND) remains one of the most controversial topics in the management of clinically localized prostate cancer. Although most urologists agree on its benefit for staging and prognostication, the role of the ePLND in cancer control continues to be debated. The increased perioperative morbidity makes it unpalatable, especially in patients with low likelihood of lymph node disease. With the advent of robotic assisted laparoscopic prostatectomy, many surgeons were slow to adopt ePLND in the robotic setting. In this study, we summarize the evidence for the prognostic and therapeutic roles of ePLND, review the clinical tools used for lymph node metastasis prediction and survey the numerous experiences of ePLND compiled by robotic urologic surgeons over the years.