Anatomical localization and clinical impact of sentinel lymph nodes based on patterns of pelvic lymphatic drainage in clinically localized prostate cancer

Japanese expert consensus on the standardization of robot-assisted pelvic lymph node dissection in urological surgery: Extent of pelvic lymph node and surgical technique

Pelvic lymph node dissection (PLND) is important for accurate staging and prognosis of prostate and/or bladder cancer. Several guidelines recommend extended PLND for patients with these cancers. However, the therapeutic benefits of extended PLND are unclear. One major reason is that the extent of PLND is not clearly defined. Thus, the working group for standardization of robot-assisted PLND, including nine experienced urologists for PLND in Japan, was launched in January 2023 by the Japanese Society of Endourology and Robotics. This study summarized the discussions to define the individual extent of PLND in urological surgery in a consensus meeting among these experienced urologists. The consensus meeting determined the extent of PLND based on arteries (veins) and anatomical membrane structures rather than a vague concept or approach toward PLND. This concept is expected to allow surgeons to implement the same extent of PLND. Finally, after a total of 10 online web conferences were held, we determined the extent of PLND for the obturator lymph node (LN) area, the internal iliac LN area, the external and common iliac LN area, and the presacral LN area according to the above rules. The extent of PLND suggested here currently does not have a clear therapeutic rationale. Therefore, the extent of our proposed PLND is by no means mandatory. We hope our definition of the extent of PLND will be supported by further evidence of therapeutic benefits for urologic cancers.

The role and controversy of pelvic lymph node dissection in prostate cancer treatment: a focused review

Pelvic lymph node dissection (PLND) is commonly performed alongside radical prostatectomy. Its primary objective is to determine the lymphatic staging of prostate tumors by removing lymph nodes involved in lymphatic drainage. This aids in guiding subsequent treatment and removing metastatic foci, potentially offering significant therapeutic benefits. Despite varying recommendations from clinical practice guidelines across countries, the actual implementation of PLND is inconsistent, partly due to debates over its therapeutic value. While high-quality evidence supporting the superiority of PLND in oncological outcomes is lacking, its role in increasing surgical time and risk of complications is well-recognized. Despite these concerns, PLND remains the gold standard for lymph node staging in prostate cancer, providing invaluable staging information unattainable by other techniques. This article reviews PLND's scope, guideline perspectives, implementation status, oncologic and non-oncologic outcomes, alternatives, and future research needs.

[99mTc]Tc-HYNIC-ALUG SPECT/CT in the initial staging of 227 consecutive patients with newly diagnosed prostate cancer: a 5-year monocentric retrospective study

Purpose

The purpose of this study was to assess the effectiveness of [99mTc]Tc-HYNIC-ALUG SPECT/CT in the initial staging of patients with newly diagnosed PCa.

Methods

A retrospective analysis was conducted on 227 consecutive patients who underwent [99mTc]Tc-HYNIC-ALUG SPECT/CT imaging for the primary staging of newly diagnosed PCa. The presence and location of PSMA-positive lesions were determined, and the maximum standardized uptake values (SUVmax) of the primary prostate tumor were also measured. The metastatic findings and SUVmax were stratified according to International Society of Urological Pathology (ISUP) grade, prostate-specific antigen (PSA) levels, and D'Amico classification. Furthermore, the [99mTc]Tc-HYNIC-ALUG SPECT/CT findings were compared to the histopathological findings in patients who had undergone radical prostatectomy with pelvic lymph node dissection (PLND).

Results

Of the 227 patients, 92.1% (209/227) had positive [99mTc]Tc-HYNIC-ALUG SPECT/CT findings. Advanced disease was detected in 38.8% (88/227) of the patients and was positively correlated with increasing ISUP grade and PSA levels. Lymph node metastases (both pelvic and extrapelvic), bone metastases, and visceral metastases were detected in 30.0% (68/227), 25.6% (58/227), and 3.1% (7/227) of the patients, respectively. For the 129 patients who underwent radical prostatectomy with PLND, the sensitivity of [99mTc]Tc-HYNIC-ALUG SPECT/CT in the evaluation of PCa was 90.7% (117/129). The sensitivity, specificity, accuracy, and positive and negative predictive values for detecting pelvic lymph node metastases on [99mTc]Tc-HYNIC-ALUG SPECT/CT were 23.5% (12/51), 93.6% (73/78), 65.9% (85/129), 70.6% (12/17), and 65.2% (73/112), respectively. Among the 209 patients with PSMA-avid primary prostate disease, the SUVmax of the primary prostate tumor was significantly associated with ISUP grade (p<0.0001), PSA levels (p<0.0001), D'Amico classification (p<0.0001), and advanced disease (p<0.0001). Receiver operating characteristic (ROC) analysis revealed that a PSA level >19.8 ng/ml and SUVmax of the primary prostate tumor >7.4 had a sensitivity of 71.6% and 71.6% and specificity of 76.9% and 82.6%, respectively, for detecting metastatic disease.

Conclusions

[99mTc]Tc-HYNIC-ALUG SPECT/CT emerges as a valuable imaging tool for the initial staging of newly diagnosed PCa. The presence of advanced disease and the SUVmax of the primary prostate tumor were positively correlated with ISUP grade and PSA levels.

Standardization of robot-assisted pelvic lymph node dissection-Development of a common understanding of regional anatomy and surgical technique based on cross-disciplinary discussion among colorectal surgery, urology, and gynecology

BACKGROUND

Pelvic lymph node dissection is a procedure performed in gastroenterological surgery, urology, and gynecology. However, due to discrepancies in the understanding of pelvic anatomy among these departments, cross-disciplinary discussions have not been easy. Recently, with the rapid spread of robotic surgery, the importance of visual information in understanding pelvic anatomy has become even more significant. In this project, we attempted to clarify a shared understanding of pelvic anatomy through cross-disciplinary discussions.

METHOD

From May 2020 to November 2021, a total of 11 discussions were held entirely online with 5 colorectal surgery specialists, 4 urologists, and 4 gynecologists. The discussions focused on evidence from each specialty and surgical videos, aiming to create a universally understandable pelvic anatomical illustration.

RESULTS

The common area of dissection recognized across the three departments was identified as the obturator lymph nodes. A dynamic illustration of pelvic anatomy was created. In addition to a bird's-eye view of the pelvis, a pelvic half view was developed to enhance understanding of the deeper pelvic anatomy. The following insights were incorporated into the illustration: (1) the cardinal ligament in gynecology partly overlaps with the vesicohypogastric fascia in colorectal surgery; (2) the obturator lymph nodes continue cephalad into the fossa of Marcille in urology; and (3) the deep uterine vein in gynecology corresponds to the inferior vesical vein in colorectal surgery.

CONCLUSION

Based on the dynamic illustration of pelvic anatomy from cross-disciplinary discussions, we anticipate advancements in pelvic lymph node dissection aiming for curative and safe outcomes.

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.

Simplified approach to the medial internal iliac region using a uretero-hypogastric nerve fascia development procedure for extended pelvic lymph node dissection during robot-assisted radical prostatectomy for high-risk prostate cancer

INTRODUCTION

Although several clinical guidelines for prostate cancer (PC) recommend extended pelvic lymph node dissection (ePLND) during radical prostatectomy for high-risk cases, there are several issues to consider, including certain technical aspects. A simplified approach to the medial internal iliac region and paravesical arteries has not been established. The uretero-hypogastric nerve fascia (UHF) envelopes the ureter, hypogastric nerve, and pelvic autonomic nerves. To preserve the UHF, it is possible to approach the medial side of the internal iliac vessels without injuring any important tissue. We analyzed technical feasibility and lymph node (LN) yields.

PATIENTS AND METHODS

After obtaining institutional review board approval, 265 high-risk PC patients with ePLND were identified. A da Vinci S or Xi robotic surgical system (Intuitive Surgical, Sunnyvale, CA, USA) was used. We divided the patients into conventional (non-UHF) method and modified (UHF) groups. The numbers of LNs removed, procedure-related complications, and surgical outcomes were analyzed.

RESULTS

The median number of LNs removed was 19.0 in the non-UHF group and 22.0 in the UHF group (p = 0.004). Significantly more LNs were removed from the internal iliac region in the UHF group (p = 0.042). There was no difference in overall operative, console, or LN dissection time, or the severe complication rate (Clavien-Dindo grade ≥ III), between the non-UHF and UHF groups.

CONCLUSIONS

Our simplified approach using the UHF development technique is technically feasible, has no major complications, and allows for the removal of significantly more LNs compared with the conventional method.

The application of indocyanine green in guiding prostate cancer treatment

Objective

Indocyanine green (ICG) with near-infrared fluorescence absorption is approved by the United States Food and Drug Administration for clinical applications in angiography, blood flow evaluation, and liver function assessment. It has strong optical absorption in the near-infrared region, where light can penetrate deepest into biological tissue. We sought to review its value in guiding prostate cancer treatment.

Methods

All related literature at PubMed from January 2000 to December 2020 were reviewed.

Results

Multiple preclinical studies have demonstrated the usefulness of ICG in identifying prostate cancer by using different engineering techniques. Clinical studies have demonstrated the usefulness of ICG in guiding sentinel node dissection during radical prostatectomy, and possible better preservation of neurovascular bundle by identifying landmark prostatic arteries. New techniques such as adding fluorescein in additional to ICG were tested in a limited number of patients with encouraging result. In addition, the use of the ICG was shown to be safe. Even though there are encouraging results, it does not carry sufficient sensitivity and specificity in replacing extended pelvic lymph node dissection during radical prostatectomy.

Conclusion

Multiple preclinical and clinical studies have shown the usefulness of ICG in identifying and guiding treatment for prostate cancer. Larger randomized prospective studies are warranted to further test its usefulness and find new modified approaches.

Pelvic Lymphadenectomy May Not Improve Biochemical Recurrence-Free Survival in Patients with Prostate Cancer Treated with Robot-Assisted Radical Prostatectomy in Japan (The MSUG94 Group)

In this multicenter retrospective cohort study, we aimed to evaluate whether pelvic lymph node dissection (PLND) improved biochemical recurrence (BCR) in patients with prostate cancer (PCa) who underwent robot-assisted radical prostatectomy (RARP) in Japan. A multicenter retrospective cohort study of 3195 PCa patients undergoing RARP at nine institutions in Japan was conducted. Enrolled patients were divided into two groups: those who underwent RARP without PLND (non-PLND group) and those who underwent PLND (PLND group). The primary endpoint was biochemical recurrence-free survival (BRFS) in PCa patients who underwent PLND. We developed a propensity score analysis to reduce the effects of selection bias and potential confounding factors. Propensity score matching resulted in 1210 patients being enrolled in the study. The 2-year BRFS rate was 95.0% for all patients, 95.8% for the non-PLND group, and 94.3% for the PLND group (p = 0.855). For the all-risk group according to the National Comprehensive Cancer Network risk stratification, there were no significant differences between patients who did and did not undergo PLND. Based on the results of the log-rank study, PLND may be unnecessary for patients with PCa undergoing RARP.

Laparoscopic partial nephrectomy for the horseshoe kidney with indocyanine green fluorescence guidance under the modified supine position

Introduction

Owing to the complexity of their blood supply, renal tumors in horseshoe kidneys are sometimes technically challenging to resect through laparoscopic procedures.

Case presentation

A 75-year-old man presented with a 3-cm lower-pole mass in the right moiety of the horseshoe kidney. Indocyanine green administration allowed for the identification of the tumor's feeding artery, which was selectively clamped to perform laparoscopic partial nephrectomy. During the procedure, the patient was positioned in the modified supine position (30° semi-lateral position), which enabled us to approach the branch of the left renal artery. Postoperative pathologic examination of the resected mass confirmed the diagnosis of pT1a clear cell renal cell carcinoma with negative surgical margins.

Conclusion

Our novel laparoscopic approach with indocyanine green fluorescence in the modified supine position facilitates the identification of and access to the tumor's feeding artery. This technique is advantageous for laparoscopic partial nephrectomy in patients with horseshoe kidney.

Performance of Indocyanine Green Fluorescence for Detecting Lymph Node Metastasis in Prostate Cancer: A Systematic Review and Meta-analysis

PURPOSE

The use of sentinel lymph node dissection in several cancers has been gaining attention with the emergence of indocyanine green fluorescence. We performed a meta-analysis to assess the diagnostic performance of indocyanine green fluorescence in detecting lymph node metastasis in prostate cancer patients.

METHODS

A literature search was conducted using PubMed, Cochrane Library, and SCOPUS on November 30, 2020, to identify eligible studies. Studies were eligible if they investigated the diagnostic performance of indocyanine green fluorescence before pelvic lymph node dissection in prostate cancer patients and reported the number of true positives, false positives, false negatives, and true negatives on lymph node-based analysis in comparison to histopathologic findings in the dissected specimen.

RESULTS

Our systematic review covered 11 studies published between 2011 and 2020, with 519 patients, and our meta-analysis included 9 studies with 479 patients. Based on lymph node analysis of indocyanine green fluorescence, the results showed pooled sensitivity and specificity at 0.75 (95% confidence interval [CI] 0.49 to 0.90) and 0.66 (95% CI 0.61 to 0.70), respectively. The diagnostic odds ratio was 6.0 (95%CI 2 to 21). Several lymphatic drainage routes also showed sentinel lymph nodes localized outside the ordinal pelvic lymph node template.

CONCLUSIONS

We noted relatively low diagnostic performance for lymph node metastasis, suggesting that indocyanine fluorescence may not currently be a viable alternative to pelvic lymph node dissection in prostate cancer patients. However, this technique shows novel lymphatic drainage routes and underscores the importance of lymph nodes not removed in ordinary dissection.

Clear identification of the rare solitary external iliac lymph node metastasis of testicular cancer by using indocyanine green fluorescence guidance

INTRODUCTION

There are few reports on indocyanine green fluorescence-guided surgery in testis-related diseases.

CASE PRESENTATION

A 38-year-old man underwent orchiectomy for left testicular cancer. Pathological diagnosis was pT1 seminoma. Seven years after the surgery, solitary left external iliac lymph node metastasis was suspected. We decided to perform laparoscopic lymph node dissection combined with indocyanine green fluorescence injection. During the operation, we injected indocyanine green fluorescence into his left inner inguinal ring and found that the lymph node was directly drained from the injection point. The pathological diagnosis of the indocyanine green fluorescence-positive left external iliac lymph node was testicular cancer metastasis.

CONCLUSION

We experienced a case of solitary left external iliac lymph node recurrence in testicular cancer. Using indocyanine green fluorescence injection, we could visualize the lymphatic drainage route, which helped us identify the lymph node as the primary landing site of metastasis.

Indocyanine Green Fluorescence-Guided Partial Cystectomy and Pelvic Lymphadenectomy for Urachal Carcinoma

Background: Intraoperative indocyanine green near-infrared fluorescence guidance is an emerging optical imaging technology to facilitate better understanding of surgical landmarks. Herein, this technique was applied during the surgery for urachal carcinoma. Case Presentation: A 50-year-old man with urachal carcinoma underwent laparoscopic partial cystectomy and pelvic lymph node dissection (PLND). Before the laparoscopic surgery, indocyanine green was injected cystoscopically around the tumor at the submucosa level. The tumor location and lymph drainage were clearly viewed. The lymphatic flow was along the superior vesical artery and the umbilical ligament. The obturator and external lymph nodes were not fluoresced. Template PLND was performed. Partial cystectomy was completed with cystoscopic monitoring of the margin and with endoscopic stapler to avoid tumor spillage. Conclusion: Intraoperative indocyanine green fluorescence views lymph drainage and tumor location and is useful to improve the quality of PLND and partial cystectomy.

68Ga-PSMA PET/CT for Primary Lymph Node and Distant Metastasis NM Staging of High-Risk Prostate Cancer

With the largest high-risk prostate cancer (PCa) cohort to date undergoing ⁶⁸Ga-prostate-specific membrane antigen (PSMA) PET/CT primary staging, we aimed to, first, characterize the metastatic spread of PCa in relation to tumor ⁶⁸Ga-PSMA uptake and the D'Amico classification and, second, compare ⁶⁸Ga-PSMA PET/CT findings with radical prostatectomy and pelvic lymph node dissection (PLND) histopathology findings. Methods: The study included 691 consecutive newly diagnosed, biopsy-proven, treatment-naïve, D'Amico high-risk PCa patients primary-staged by ⁶⁸Ga-PSMA PET/CT. PSMA SUV_max and metastatic findings were compared with prostate-specific antigen level, International Society of Urological Pathology (ISUP) grade, and clinical stage as traditional risk stratification parameters. Moreover, ⁶⁸Ga-PSMA PET/CT findings were compared with histology findings in radical prostatectomy patients undergoing PLND. Undetected lymph node metastases (LNMs) underwent immunohistochemical PSMA staining. Results: Advanced disease (N1/M1) was observed in 35.3% of patients (244/691) and was associated with increasing prostate-specific antigen level, ISUP grade, and clinical stage. LNMs (N1/M1a) were detected in 31.4% (217/691) and bone metastases (M1b) in 16.8% (116/691). Advanced disease frequencies in patients with ISUP grades 2 and 3 were 10.8% (11/102) and 37.1% (33/89), respectively. Risk of advanced disease for cT2a, cT2b, and cT2c tumors was almost equal (24.2%, 27.9%, and 22.4%, respectively). We observed a weak correlation between SUV_max and biopsy ISUP grade (ρ = 0.21; P < 0.001) and a modest correlation between SUV_max and postprostatectomy ISUP grade (ρ = 0.38; P < 0.001). Sensitivity, specificity, positive and negative predictive value, and accuracy for LNM detection on ⁶⁸Ga-PSMA PET/CT in the PLND cohort were 30.6%, 96.5%, 68.8%, 84.5%, and 83.1%, respectively. Undetected LNMs either were micrometastases located in the lymph node border or were without PSMA expression. Conclusion: In this high-risk PCa cohort, we identified advanced disease in about one third at diagnosis. ISUP grade was the superior predictor for advanced disease at diagnosis. We found a significant difference in frequency of advanced disease between ISUP grades 2 and 3, as supports the Gleason score 7 subdivision. Interestingly, we observed no significant differences in risk of advanced disease when comparing the different cT2 stages. The undetected LNMs were either PSMA-negative or micrometastases.

Sentinel node evaluation in prostate cancer

Sentinel lymph node (SLN) based pelvic lymph node dissection (PLND) in prostate cancer (PCa) is appealing over the time, cost and morbidity classically attributed to conventional PLND during radical prostatectomy. The initial report of feasibility of the SLN concept in prostate cancer was nearly 20 years ago. However, PLND based on the SLN concept, either SLN biopsy of a single node or targeted SLN dissection of multiple nodes, is still considered investigational in PCa. To better appreciate the challenges, and potential solutions, associated with SLN-based PLND in PCa, this review will discuss the rationale behind PLND in PCa and evaluate current SLN efforts in the most commonly diagnosed malignancy in men in the US.