Radio-guided sentinel lymph node detection and lymph node mapping in invasive urinary bladder cancer: a prospective clinical study

Near-infrared fluorescence lymph node template region dissection plus backup lymphadenectomy in open radical cystectomy for bladder cancer using an innovative handheld device: A single center experience

BACKGROUND

The extent of pelvic lymphadenectomy (PLND) as part of radical cystectomy (RC) for bladder cancer (BC) remains unclear. Sentinel-based and lymphangiographic approaches could lead to reduced morbidity without sacrificing oncologic safety.

OBJECTIVE

To evaluate the feasibility and diagnostic value of fluorescence-guided template sentinel region dissection (FTD) using a handheld near-infrared fluorescence (NIRF) camera in open radical cystectomy.

DESIGN, SETTING, AND PARTICIPANTS

After peritumoral cystoscopic injection of indocyanine green (ICG) 21 patients underwent open RC with FTD due to BC between June 2019 and June 2021. Intraoperatively, the FIS-00 Hamamatsu Photonics® NIRF camera was used to identify and resect fluorescent template sentinel regions (FTRs) followed by extended pelvic lymphadenectomy (ePLND) as oncological back-up.

OUTCOME MEASUREMENT AND STATISTICAL ANALYSIS

Descriptive analysis of positive and negative results per template region.

RESULTS AND LIMITATIONS

FTRs were identified in all 21 cases. Median time (range) from ICG injection to fluorescence detection was 75 (55-125) minutes. On average (SD), 33.4 (9.6) lymph nodes were dissected per patient. Considering template regions as the basis of analysis, 67 (38.3%) of 175 resected regions were NIRF-positive, with 13 (7.4%) regions harboring lymph node metastases. We found no metastatic lymph nodes in NIRF-negative template regions. Outside the standard template, two NIRF-positive benign nodes were identified.

CONCLUSION

The concept of NIRF-guided FTD proved for this group all lymph node metastases to be found in NIRF-positive template regions. Pending validation in a larger collective, resection of approximately 40% of standard regions may be sufficient and may result in less morbidity.

Vascular Enlargement as a Predictor of Nodal Involvement in Bladder Cancer

In bladder cancer (BC), the evaluation of lymph node (LN) involvement at preoperative imaging lacks specificity. Since neoangiogenesis is paired with lymphatic involvement, this study aims to evaluate the presence of perivesical venous ectasia as an indirect sign of LN involvement, together with other conventional CT findings. All the patients who underwent radical cystectomy (RC) for BC between January 2017 and December 2019 with available preoperative contrast-enhanced CT (CECT) within 1 month before surgery were included. Patients without available pathological reports (and pTNM stage) or who underwent neoadjuvant treatments and palliative RC were excluded. Two readers in blind assessed the nodal shape and hilum, the short axis, and the contrast enhancement of suspicious pelvic LNs, the Largest Venous Diameter (LVD) efferent to the lesion, and the extravesical tumor invasion. In total, 38 patients (33 males) were included: 17 pT2, 17 pT3, 4 pT4; pN+: 20/38. LN short axis > 5 mm, LN enhancement, and LVD > 3 mm were significantly correlated with N+ at pathology. LVD > 3 mm had a significantly higher sensitivity and specificity (≥90%, AUC = 0.949) and was an independent predictor (p = 0.0016).

Diagnostic Value of the Sentinel Lymph Node Technique in Patients with Muscle-Invasive Bladder Cancer

BACKGROUND

The optimal limits of the bilateral pelvic lymph node dissection (PLND) template in bladder cancer treatment remain controversial. This study aimed to investigate whether radio-guided sentinel node (SLN) detection is a reliable technique for the perioperative localisation of potential lymphatic metastasis during cystectomy for muscle-invasive bladder cancer (MIBC).

MATERIALS AND METHODS

We studied 54 patients with pT2-pT4 MIBC who underwent cystectomy with extended PLND (ePLND) augmented by the SLN technique. The identification of SLN was performed by preoperative SPECT/CT hybrid lymphoscintigraphy using peritumoral injection of nanocolloid-Tc-99m, followed by intraoperative navigation with a handheld γ-probe. All nodal specimens were collected separately and then fixed in formalin, stained with haematoxylin and eosin, and examined by an experienced uropathologist.

RESULTS

A total of 1414 LNs were resected and examined for the presence of metastases. The mean number of harvested LNs was 26 (range: 11-50) per patient. In 51 of 54 patients, 192 SLNs were resected. In addition, 20/192 (10.4%) SLNs were located outside of the ePLND area. Overall, 72 metastatic LNs (LN+) were found in 22 of 54 patients (40.7%) and in 24/192 SLNs (12.5%). The SLN technique detected LN+ in 14 of 22 (64%) patients. The SLNs were the only sites of metastasis (SLN+ = LN+) in 6 of 22 (27.3%) LN+ patients, including two cases with foci located in the pararectal region. The diagnostic values for the sensitivity, specificity, positive predictive value, and false-negative rate for the SLN technique were 66.66%, 4.16%, 28.57%, and 33.33%, respectively. Extended lymphadenectomy and its combination with the SLN technique enabled the correct assessment in 96.3 and 100% of patients, respectively.

CONCLUSIONS

The combination of ePLND and SLN provides a better pN assessment compared to ePLND alone. Although the SLN technique has restrictions that limit its diagnostic value, its use as an addition to lymphadenectomy allows for the visualisation of nonstandard lymph drainage pathways that may be potential metastatic routes.

The emerging role of cell cycle protein p53 expression by tumor cells and M2-macrophage infiltration in urinary bladder cancer

PURPOSE

To investigate the association between p53 expression in tumor cells and intratumoral macrophage infiltration in muscle-invasive urinary bladder cancer (MIBC) in relation to clinical and pathological variables and outcomes after radical cystectomy.

METHODS

Tumor specimens of the primary tumor from patients treated with radical cystectomy for MIBC were immunostained with the M2-macrophage-specific marker CD163 and the cell cycle protein p53. The expression of these markers was analyzed in relation to patients´ and tumor characteristics and outcome.

RESULTS

Out of 100 patients with urinary bladder cancer (UBC) pathological stage T1-4 N0-3 M0, 77% were men. The patients had a median age of 69 years and 80% had nonorgan-confined tumors (pT3-4). Lymph node metastasis was found in 42 (42%) of all patients. P53-positive expressions were found in 63 (63%) patients. Strong macrophage infiltration in the tumor microenvironment was shown in 74 (74%) patients. Combinations of CD163/p53 status were as follows: CD163+/p53+, 50%; CD163+/p53-, 24%; CD163-/p53+, 13%; and CD163-/p53-, 13%. Patients with CD163+/P53+ had higher proportions of organ-confined tumors.

CONCLUSIONS

In the present series of patients with MIBC treated with cystectomy, we found that high CD163+ macrophage infiltration in the tumor micro-environment often was combined with p53+ cancer cells. This simultaneous expression of p53 by tumor cells and increased infiltration of M2-macrophages in the tumor microenvironment was associated with improved CSS, which might indicate a possible protective effect of M2 macrophages in p53+ tumors. Further investigations are needed to explore the biological relation between mutational burden and immune profile in MIBC.

Thyroglobulin expression, Ki-67 index, and lymph node ratio in the prognostic assessment of papillary thyroid cancer

The clinical significance of thyroglobulin (Tg) expression in papillary thyroid cancer (PTC) has not been systematically explored in relation to the Ki-67 index, lymph node ratio (LNR), or other conventional prognostic predictors. In this retrospective study of 327 patients with PTC, we investigated the immunohistochemical expression of Tg in both primary tumors and their matching lymph node metastases in relation to the Ki-67 index, LNR, and clinical data. Tumoral Tg immunoreactivity was inversely correlated to the Ki-67 index and tumor recurrence. The Ki-67 index was higher in lymph node metastases (mean 4%) than in the primary tumors (mean 3%). Reduced Tg expression, estimated as 0-25% Tg positive tumor cells, was more common in lymph node metastases compared to primary tumors. In addition to advanced metastatic burden (defined as N1b stage and LNR ≥ 21%), low Tg expression (0-25% positive tumor cells) in lymph node metastases had a significant prognostic impact with shorter recurrence-free survival. These findings support the potential value of histopathological assessment of Tg expression and Ki-67 index in lymph node metastases as complementary predictors to anticipate the prognosis of PTC patients better.

Pelvic lymph node dissection in prostate and bladder cancers

Prostate cancer and bladder cancer accounts for approximately 13.5% and 3% of all male cancers and all newly diagnosed cancers (regardless sex), respectively. Thus, these cancers represent a major health and economic burden globally. The knowledge of lymph node status is an integral part of the management of any solid tumor. In the urological field, pelvic lymph node dissection (PLND) is of paramount importance in the diagnosis, management, and prognosis of prostate and bladder cancers. However, PLND may be associated with several comorbidities. In this narrative review, the most recent updates concerning the patterns and incidence of lymph node metastasis, the role of different imaging studies and nomograms in determining patients' eligibility for PLND, and the anatomical templates of PLND in urologic patients with bladder or prostate cancer will be discussed.

Excitation coil for sentinel lymph node harvesting: design, digital twin and prototype

A recently developed prototype (Laparoscopic Differential Magnetometer, in short LapDiffMag) identifies magnetic tracer accumulated inside sentinel lymph nodes (SLNs) during clinical laparoscopic procedures. The LapDiffMag relies on excitation of superparamagnetic iron oxide nanoparticles (SPIONs) and subsequent laparoscopic detection based on a nonlinear detection principle. The prototype uses an excitation coil to generate a magnetic field needed to activate SPIONs. This study reports on the process of developing a new excitation coil by describing the design choices based upon clinical requirements, by modeling delivered magnetic field using digital twin, and by comparing the magnetic fields of modeled and manufactured prototype. Digital twin technology was used to produce relevant and reliable data to demonstrate the safety and effectiveness of the excitation coil. The magnetic field originating from manufactured prototype was validated at two different heights above the excitation coil and have shown a good concordance to the data generated by its digital twin. Clinical Relevance- Current standard-of-care for a variety of tumor types consists of minimally invasive radical resection of primary tumor and regional lymph nodes (LNs). The newly introduced excitation coil will (after full validation) enable minimally invasive harvesting of sentinel LNs by means of magnetic tracer detection.

Methods of Sentinel Lymph Node Detection and Management in Urinary Bladder Cancer—A Narrative Review

Introduction: Detection of lymph node status in bladder cancer significantly impacts clinical decisions regarding its management. There is a wide range of detection modalities for this task, including lymphoscintigraphy, computed tomography, magnetic resonance imaging, single-photon emission computed tomography, positron emission tomography, and fluoroscopy. We aimed to study the pre- and intraoperative detection modalities of sentinel lymph nodes in urinary bladder cancer. Method: This narrative review was performed by searching the PubMed and EMBASE libraries using the following search terms: (“Transitional cell carcinoma of the bladder” OR “urothelial cancer” OR “urinary bladder cancer” OR “bladder cancer”) AND ((“sentinel lymph node”) OR (“lymphatic mapping”) OR (“lymphoscintigraphy”) OR (“lymphangiography”) OR (“lymph node metastases”)). Studies analysing the effectiveness and outcomes of sentinel lymph node detection in bladder cancer were included, while non-English language, duplicates, and non-article studies were excluded. After analysing the libraries and a further manual search of bibliographies, 31 studies were included in this paper. We followed the RAMESES publication standard for narrative reviews to produce this paper. Results: Of the 31 studies included, 7 studies included multiple detection methods; 5 studies included lymphoscintigraphy; 5 studies included computed tomography and/or single-photon emission computed tomography; 5 studies included fluoroscopy; 4 studies included magnetic resonance imaging; and 5 studies included positron emission tomography. Discussion: Anatomical, radioactive, and functional detection modalities have been studied independently and in combination. The consensus is that preoperative detection with imaging helps guide surgical management and intraoperative detection methods help capture any lymph nodes that may have been missed. Each of these types of detection represent their own set of benefits and drawbacks, but there is currently limited evidence to support any change in overall practice to replace conventional staging.

The Usefulness of Lymphadenectomy in Bladder Cancer-Current Status

The purpose of this review is to present the current status of lymph node dissection (LND) during radical cystectomy in patients with bladder cancer (BCa). Despite the growing body of evidence of LND utility at the time of radical cystectomy (RC) in high-risk nonmuscle-invasive and muscle-invasive BCa (MIBC), therapeutic and prognostic value and optimal extent of LND remain unsolved issues. Recently published results of the first prospective, a randomized trial assessing the therapeutic benefit of extended versus limited LND during RC, failed to demonstrate survival improvement with the extended template. Although LND is the most accurate staging procedure, the direct therapeutic effect is still not evident from the current literature, limiting the possibility of establishing clear recommendations. This indicates the need for robust and adequately powered clinical trials.

The Clinical Significance of Lymph Node Ratio and Ki-67 Expression in Papillary Thyroid Cancer

BACKGROUND

The N stage in papillary thyroid cancer (PTC) is an important prognostic factor based on anatomical localization of cervical lymph nodes (LNs) only and not the extent of lymphatic metastasis. In this retrospective study, the clinical significance of lymph node ratio (LNR) and tumor cell proliferation in relation to the conventional classification of PTC was explored.

METHODS

Patients diagnosed with PTC at the Karolinska University Hospital in Stockholm, Sweden, during the years 2009-2011 were included. The LNR, defined as the number of metastatic LNs divided by the total number of LNs investigated, and the Ki-67 index were analyzed in relation to clinical data.

RESULTS

The median number of LN removed was 16 with the following N stage distribution: N0 (26%), N1a (45%), and N1b (29%). A Ki-67 index of ≥3% was significantly correlated with the presence of metastases and tumor recurrence with a sensitivity of 50% and specificity of 80% (p = 0.015). Lymph node ratio ≥21% was related to tumor recurrence with sensitivity of 89% and specificity of 70% (p = 0.006). Patients with LN metastases in the lateral cervical compartment only had significantly lower LNR (14.5%) compared to those with both central and lateral cervical metastases (39.5%) (p = 0.004) and exhibited no tumor recurrence. Increased Ki-67 index was significantly related to LNR ≥21% (p = 0.023) but was not associated with N stage.

CONCLUSIONS

The Ki-67 proliferation index and LNR may better reflect the malignant behavior of PTC compared to the anatomical classification of LN metastases solely.

The evolving role of lymphadenectomy for bladder cancer: why, when, and how

Radical cystectomy (RC) represents a standard treatment for non-metastatic muscle-invasive and select high-risk non-muscle invasive bladder cancer. Lymphadenectomy performed at time of RC identifies nodal metastases in up to 25% of patients despite normal imaging. There has been an increasing utilization of pelvic lymph node dissection (PLND) with RC since 1950, and in fact lymph node dissection is now recommended in contemporary National Comprehensive Cancer Network (NCCN) guidelines. Benefits of removing of nodal disease include improved staging, guidance for adjuvant treatment, and potentially improved oncologic outcomes. Advantages of dissection have been suggested among both node-negative and node-positive patients. Numerous studies have attempted to define the optimal dissection characteristics of lymphadenectomy with regard to nodal yield and anatomic boundaries of dissection. The ideal extent of lymphadenectomy remains uncertain due to the retrospective and non-randomized nature of the majority of existing reports, which are thereby limited by significant confounding and selection bias. Two randomized controlled trials have investigated this issue, one of which LEA AUO AB 25/02 recently reported its outcomes, demonstrating no significant improvement in 5-year outcomes with an extended dissection. Meanwhile, the Southwest Oncology Group 1011 trial has completed enrollment and data are maturing. While current data preclude definitive recommendations, herein we review the why, when, and how to perform a PLND for bladder cancer.

IL-16 processing in sentinel node regulatory T cells is a factor in bladder cancer immunity

In the effort of developing new immunotherapies, the sentinel node (SN) has proven a promising source from which to harness an effective antitumour T cell response. However, tumour immune escape, a process in which regulatory T cells (Tregs) play a central role, remains a major limiting factor. Therefore, there is a clear need to increase the knowledge of Treg function and signalling in sentinel nodes. Here, we set out to explore whether the proteome in SN-resident T cells is altered by the tumour and to identify key proteins in SN T cell signalling, focusing on Tregs. Five patients with muscle-invasive urothelial bladder cancer were prospectively included. Mass spectrometry was performed on two patients, with validation and functional studies being performed on three additional patients and four healthy donors. At cystectomy, SN, non-SN lymph nodes and peripheral blood samples were collected from the patients and T cell subsets isolated through flow cytometry before downstream experiments. Proteomic analysis indicated that growth and immune signalling pathways are upregulated in SN-resident Tregs. Furthermore, centrality analysis identified the cytokine IL-16 to be central in the SN-Treg signalling network. We show that tumour-released factors, through activating caspase-3, increase Treg IL-16 processing into bioactive forms, reinforcing Treg suppressive capacity. In conclusion, we provide evidence that Tregs exposed to secreted factors from bladder tumours show increased immune and growth signalling and altered IL-16 processing which translates to enhanced Treg suppressive function, indicating altered IL-16 signalling as a novel tumour immune escape mechanism.

Sentinel lymph node biopsy in muscle-invasive bladder cancer: single-center experience

OBJECTIVE

In this study, the validity of sentinel node biopsy procedure as our index test was assessed and compared with bilateral pelvic lymphadenectomy for staging and detecting the regional lymph nodes metastasis in patients with muscle-invasive bladder cancer (MIBC).

METHODS

Consecutive series of cases with T1-T4 urothelial MIBC were included. Following the injection of radiotracer, sentinel nodes were sought using a handheld gamma probe and all hot nodes were harvested. Bilateral pelvic lymphadenectomy was done for all patients following sentinel node biopsy. The tumor specimen, sentinel nodes, and excised lymph nodes were evaluated histopathologically. Same as the other midline tumors, detection rate and false negative rates were calculated using patient basis and side basis methods.

RESULTS

By evaluating each patient as a unit of analysis, sentinel nodes were detected in 35 of 41 patients (85%), 13/16 (81%) of the neoadjuvant chemotherapy (NAC) and 22/25 (88%) of the no-neoadjuvant chemotherapy (No-NAC) participants. The false negative rate was 3/7 (42%): 1/3 (33%) for NAC, and 2/4 (50%) for No-NAC patients. By evaluating each hemipelvis as a unit of analysis, sentinel nodes were detected in 53 of 82 hemipelves (65%), 19/32 (66%) of the NAC, and 34/50 (68%) of the No-NAC hemipelves. No false-negative result was found by assessing each hemipelvis as a unit of analysis.

CONCLUSIONS

Sentinel node biopsy is a feasible method for lymph node staging in MIBC, including patients with a history of NAC. To optimize the sensitivity, the decision regarding the lymphadenectomy is best to be based on the pathological status of sentinel node harvested from each hemipelvis separately as the unilateral finding of a sentinel node, does not rule out the possibility of metastatic involvement of contralateral pelvic lymph nodes.

Pelvic lymph node distribution and metastases of prostate and bladder cancer: a systematic literature review and template proposal

PURPOSE

To systematically review the relevant literature that evaluates the LN topographical distribution and propose a uniform template.

METHODS

A bibliographic search of PubMed/Medline, Embase and SCOPUS was performed for studies reporting data of LN imaging and/or nodal resection.

RESULTS

101 and 26 articles met the inclusion criteria for PCa and BCa, respectively. In PCa, the most common locations of positive LNs for surgical and imaging studies were external iliac (both 38 studies), followed by obturator (38 and 37, respectively). Similarly, in BCa, the most common location of positive nodes for surgical and imaging studies were external iliac (19 and 4, respectively), followed by obturator (15 and 3 studies, respectively). In PCa, median percentages of positive external iliac nodes/patient were 12.2% and 11.6% for surgical and imaging studies, respectively while corresponding rates for BCa were 3.9% and 17.6%. There were high risks of bias across studies as well as high heterogeneity in the definition of the anatomic boundaries of lymphadenectomy templates.

CONCLUSIONS

This review highlights the lack of detailed information on exact LN templates and metastases location, which in turn hinders generation of high-quality evidence on optimal lymphadenectomy templates. Our proposed template is applicable for both imaging and surgical description and could facilitate the translation of anatomical location from imaging to surgical resection.

Fewer tumour draining sentinel nodes in patients with progressing muscle invasive bladder cancer, after neoadjuvant chemotherapy and radical cystectomy

Purpose

To examine the relationship between the number of tumour draining sentinel nodes (SNs) and pathoanatomical outcomes, in muscle-invasive bladder cancer (MIBC), in patients undergoing neoadjuvant chemotherapy (NAC) and radical cystectomy (RC).

Materials and Methods

In an ongoing prospective multicenter study, we included 230 patients with suspected urothelial MIBC from ten Swedish urological centers. All underwent TURb and clinical staging. From the cohort, 116 patients with urothelial MIBC; cT2-cT4aN0M0, underwent radical cystectomy (RC) and lymphadenectomy with SN-detection (SNd). 83 patients received cisplatin-based NAC and 33 were NAC-naïve. The number and locations of detected SNs and non-SNs were recorded for each patient. The NAC treated patients were categorized by pathoanatomical outcomes post-RC into three groups: complete responders (CR), stable disease (SD) and progressive disease (PD). Selected covariates with possible impact on SN-yield were tested in uni -and multivariate analyses for NAC-treated patients only.

Results

In NAC treated patients, the mean number of SNs was significantly higher in CR patients (3.3) and SD patients (3.6) compared with PD patients (1.4) (p = 0.034). In a linear multivariate regression model, the number of harvested nodes was the only independent variable that affected the number of SNs (p = 0.0004).

Conclusions

The number of tumor-draining SNs in NAC-treated patients was significantly lower in patients with progressive disease.

Communication Of Cancer Cells And Lymphatic Vessels In Cancer: Focus On Bladder Cancer

Bladder cancer is one of the most commonly diagnosed cancers worldwide and causes the highest lifetime treatment costs per patient. Bladder cancer is most likely to metastasize through lymphatic ducts, and once the lymph nodes are involved, the prognosis is poorly and finitely improved by current modalities. The underlying metastatic mechanism for bladder cancer is thus becoming a research focus to date. To identify relevant published data, an online search of the PubMed/Medline archives was performed to locate original articles and review articles regarding lymphangiogenesis and lymphatic metastasis in urinary bladder cancer (UBC), and was limited to articles in English published between 1998 and 2018. A further search of the clinical trials.gov search engine was conducted to identify both trials with results available and those with results not yet available. Herein, we summarized the unique mechanisms and biomarkers involved in the malignant progression of bladder cancer as well as their emerging roles in therapeutics, and that current data suggests that lymphangiogenesis and lymph node invasion are important prognostic factors for UBC. The growing knowledge about their roles in bladder cancers provides the basis for novel therapeutic strategies. In addition, more basic and clinical research needs to be conducted in order to identify further accurate predictive molecules and relevant mechanisms.