Lymph node staging in prostate cancer: perspective for the pathologist

The Potential of Iron Oxide Nanoparticle-Enhanced MRI at 7 T Compared With 3 T for Detecting Small Suspicious Lymph Nodes in Patients With Prostate Cancer

BACKGROUND

Accurate detection of lymph node (LN) metastases in prostate cancer (PCa) is a challenging but crucial step for disease staging. Ultrasmall superparamagnetic iron oxide (USPIO)-enhanced magnetic resonance imaging (MRI) enables distinction between healthy LNs and nodes suspicious for harboring metastases. When combined with MRI at an ultra-high magnetic field, an unprecedented spatial resolution can be exploited to visualize these LNs.

PURPOSE

The aim of this study was to explore USPIO-enhanced MRI at 7 T in comparison to 3 T for the detection of small suspicious LNs in the same cohort of patients with PCa.

MATERIALS AND METHODS

Twenty PCa patients with high-risk primary or recurrent disease were referred to our hospital for an investigational USPIO-enhanced 3 T MRI examination with ferumoxtran-10. With consent, they underwent a 7 T MRI on the same day. Three-dimensional anatomical and T2*-weighted images of both examinations were evaluated blinded, with an interval, by 2 readers who annotated LNs suspicious for metastases. Number, size, and level of suspicion (LoS) of LNs were paired within patients and compared between field strengths.

RESULTS

At 7 T, both readers annotated significantly more LNs compared with 3 T (474 and 284 vs 344 and 162), with 116 suspicious LNs on 7 T (range, 1-34 per patient) and 79 suspicious LNs on 3 T (range, 1-14 per patient) in 17 patients. For suspicious LNs, the median short axis diameter was 2.6 mm on 7 T (1.3-9.5 mm) and 2.8 mm for 3 T (1.7-10.4 mm, P = 0.05), with large overlap in short axis of annotated LNs between LoS groups. At 7 T, significantly more suspicious LNs had a short axis <2.5 mm compared with 3 T (44% vs 27%). Magnetic resonance imaging at 7 T provided better image quality and structure delineation and a higher LoS score for suspicious nodes.

CONCLUSIONS

In the same cohort of patients with PCa, more and more small LNs were detected on 7 T USPIO-enhanced MRI compared with 3 T MRI. Suspicious LNs are generally very small, and increased nodal size was not a good indication of suspicion for the presence of metastases. The high spatial resolution of USPIO-enhanced MRI at 7 T improves structure delineation and the visibility of very small suspicious LNs, potentially expanding the in vivo detection limits of pelvic LN metastases in PCa patients.

Influence of lymph node degeneration on metastases in prostate cancer: or why we must look for a needle in a haystack

BACKGROUND

To evaluate the incidence of lymph node degeneration and its association with nodal metastatic pattern in prostate cancer.

METHODS

A retrospective analysis of the submitted lymph node specimen of 390 prostatectomies in 2011 was performed. All lymph nodes were histologically re-evaluated and the degree of lymph node degeneration e.g. lipomatous atrophy, capsular and framework fibrosis, and calcifications as well as the lymph node size were recorded. Lymph node degeneration was compared in the anatomic regions of the pelvis as well as in lymph nodes with and without metastases of prostatic cancer.

RESULTS

Eighty-one of 6026 lymph nodes demonstrated metastases. Complete histologic examination with analysis of a complete cross-section was possible in 5173 lymph nodes including all lymph nodes with metastases. The incidence of lymph node degeneration was different across the various landing sites. Lymph node metastases were primarily detected in less degenerative and therefore more functional lymph nodes. In metastatic versus non-metastatic lymph nodes low lipomatous atrophy was reported in 84.0% versus 66.7% (p = 0.004), capsular fibrosis in 14.8% versus 35.4% (p < 0.001), calcifications in 35.8% versus 46.1% (p = 0.072) and framework fibrosis in 69.8% versus 75.3% (p = 0.53). Metastases were also identified more frequently in larger than in smaller lymph nodes (63.0% vs. 47.5%; p = 0.007).

CONCLUSIONS

Degenerative changes in pelvic lymph nodes are commonly detectable but occur with variable frequency in the various nodal landing sites in the pelvis. The degree of lymph node degeneration of single lymph nodes has a significant influence on whether a lymph node is infiltrated by tumor cells and may harbour metastases.

How Image-Guided Pathology Can Improve the Detection of Lymph Node Metastases in Prostate Cancer

ABSTRACT

Detection of lymph node (LN) metastases in prostate cancer (PCa) is pivotal for accurate staging and determining treatment options. To date, the reference standard for nodal staging is histopathological examination of all harvested surgical specimens from extended pelvic LN dissections. However, this is a labor-intensive process, and small metastatic foci can be missed due to sampling effects. With current research expanding toward using radiolabeled prostate-specific membrane antigen ligands for image-guided surgery, new opportunities arise for image-guided pathological assessment of surgical specimens. Here, we illustrate how molecular imaging can complement histopathology and improve accurate detection of LN metastases.

Updated pathology reporting standards for bladder cancer: biopsies, transurethral resections and radical cystectomies

Aim

Optimal management of bladder cancer requires an accurate, standardised and timely pathological diagnosis, and close communication between surgeons and pathologists. Here, we provide an update on pathology reporting standards of transurethral resections of the bladder and cystectomies.

Methods

We reviewed recent literature, focusing on developments between 2013 and 2021.

Results

Published reporting standards developed by pathology organizations have improved diagnosis and treatment. Tumor sub-staging and subtyping has gained increased attention. Lymph nodes continue to be an area of debate, and their staging has seen minor modifications. Several tasks, particularly regarding specimen preparation (“grossing”), are not yet standardized and offer opportunity for improvement. Molecular classification is rapidly evolving, but currently has only limited impact on management.

Conclusion

Pathological reporting of bladder cancer is continuously evolving and remains challenging in some areas. This review provides an overview of recent major developments, with a particular focus on published reporting standards.

Pathological reporting of cystectomy lymph nodes: a retrospective analysis of experience in Paris

Purpose

Pathological evaluation of pelvic lymph node (LN) dissection (PLND) is important for management of cystectomy patients. However, challenges such as unclear interobserver variability of LN counting remain. Here, we assess interobserver variability of LN measures and their clinical utility, with a focus on variant histology.

Methods

We retrieved radical cystectomy cases with PLND between 2010 and 2016 and reevaluated pathological parameters; number of total and metastatic LN, LN density (LND), length of metastatic LN and metastases, extranodal extension (ENE).

Results

We report 96 patients: median age of 71a, 34 cases pN+, 36 cases with any extent of variant histology, median follow-up 10 months. Perivesical LN were only rarely identified, but frequently metastatic (4/9). Variant histology (34 cases) frequently exhibited LN metastasis (53% of pN+ cases). Interobserver variance was poor for total LN (kappa = 0.167), excellent for positive LN (0.85) and pN staging (0.96), and mediocre for LND (0.53). ROC analysis suggests that both LND and the sum of LN metastasis length may predict outcome (AUC 0.83 and 0.75, respectively).

Conclusion

Our study confirms the notion of LND as a prognostic measure, but cautions due to strong interobserver variance of LN counts. The sum length of LN metastases could be a measure that is independent of LN counts. We find that microscopically identified perivesical LN merit particular attention. In summary, our study highlights current challenges in pathological reporting of PLND, confirms previous observations and forms a basis for further studies.

Evaluation of Fast Molecular Detection of Lymph Node Metastases in Prostate Cancer Patients Using One-Step Nucleic Acid Amplification (OSNA)

Simple Summary

Prostate cancer (PCa) is the second most common cancer and one of the highestcauses of cancer deaths among men. The presence of lymph node metastases (LNM) is the strongest prognostic factor. Histological detection of LNM is the gold standard for LN staging. In clinical practice, only fractions of LNs are examined histopathologically, resulting in missed (micro-)metastases. Biomolecular techniques can enhance the identification of LNM but are not routinely used because of high cost. One-step nucleic acid amplification (OSNA) analyzes the entire LN by detecting cytokeratin 19 mRNA as a surrogate for LNM requiring less effort and allowing intraoperative application. To verify the reliability of OSNA for the first time in PCa, we examined LNs of patients undergoing prostatectomy and sentinel lymphadenectomy. Results were compared with histopathological and immunohistochemistry findings. OSNA identified LNM equivalent to, or in cases of micrometastases, even better than enhanced histopathology, and might be useful in intraoperative decision-making in personalized LN surgery.

Abstract

Background: In clinical routine, only fractions of lymph nodes (LNs) are examined histopathologically, often resulting in missed (micro-)metastases and incorrect staging of prostate cancer (PCa). One-step nucleic acid amplification (OSNA) analyzes the entire LN by detecting cytokeratin 19 (CK19) mRNA as a surrogate for LN metastases requiring less effort than conventional biomolecular techniques. We aimed to evaluate performance of OSNA in detecting sentinel LN (SLN) metastases in PCa. Methods: SLNs (n = 534) of 64 intermediate- or high-risk PCa patients undergoing radical prostatectomy with extended and sentinel-guided lymphadenectomy were cut into slices and alternatingly assigned to OSNA and histopathology (hematoxylin-eosin staining, CK19, and CK AE1/AE3 immunohistochemistry). Sensitivity and specificity of OSNA and concordance and measure of agreement (Cohen’s kappa (κ)) between OSNA and histopathology were assessed. Results: Histopathology revealed metastases in 76 SLNs. Sensitivity and specificity of OSNA were 84.2% and 96.1%, respectively. Discordant results were recorded for 30 of 534 SLNs, revealing high concordance (94.4%). Twenty-four discordant cases were classified as micrometastases, indicating a possible allocation bias. In 18 cases, positive results were conferred only by OSNA resulting in seven LN-positive patients who were missed by histopathology. Overall, the level of agreement was high (κ = 0.78). Conclusions: OSNA provided a diagnosis that was as least as accurate as detailed histological examination and might improve LN staging in PCa.

Eliminating microscopic lymph node metastasis by performing pelvic lymph node dissection during radical prostatectomy for prostate cancer

The oncological benefit of pelvic lymph node dissection (PLND) for prostate cancer (PCa) remains unclear. The therapeutic effect of PLND on the elimination of microscopic metastases during radical prostatectomy (RP) for PCa was examined in the current study. A total of 348 Japanese patients with high- or intermediate-risk PCa without lymph node metastasis, who underwent antegrade RP at the Kyushu Cancer Center (Fukuoka, Japan) between August 1998 and May 2013 were retrospectively analyzed. The patients were divided into the standard (obturator + internal iliac nodes) group and the expanded (standard + additional nodes) group according to the extent of PLND. Preoperative and postoperative characteristics were also analyzed to determine the factors associated with prostate-specific antigen (PSA) failure. Standard and expanded PLND were performed in 70.9% (247/348) and 29.1% (101/348) of cases, respectively. The results revealed that preoperative PSA levels were the only marked difference between the two groups. No differences were observed in the other preoperative and postoperative characteristics. Furthermore, the rate of PSA recurrence in each group did not differ to a statistically significant extent (P=0.3622). Reducing the area of dissection from expanded PLND to standard PLND significantly reduced the number of dissected lymph nodes (P<0.0001). Additionally, the PSA level, clinical tumor stage, Gleason score of the biopsy specimen, pathological tumor stage and extent of PLND were all associated with PSA recurrence, as determined via multivariate Cox hazards regression analysis (P=0.0177, P=0.0023, P=0.0027, P<0.0001 and P=0.0164, respectively). In high- and intermediate-risk patients without lymph node metastasis, a greater number of lymph nodes were dissected when the extent of dissection was greater. Furthermore, the extent of PLND was a significantly associated with PSA failure. The results indicated that PLND exerted a therapeutic effect by eliminating microscopic pelvic lymph node metastases that were not detected by routine pathological examinations.

Optimal sampling of pelvic lymphadenectomy specimens following radical prostatectomy: is complete tissue submission justified?

There is currently no consensus among pathologists on the optimal method of sampling pelvic lympadenectomy specimens (PLND) in prostate cancer. We evaluated the impact of complete PLND submission on lymph node (LN) yield, detection of metastasis and laboratory workload in a series of 141 cases. Following isolation of grossly identifiable LNs/potential LNs, the remaining fatty tissue was embedded in toto. Complete PLND submission increased median LN yield from 10 (1–42) to 17 (3–57). Metastatic deposits were identified in nine non-palpable LNs, which altered the pN category in four cases (3%). The primary tumour (pT) was grade group ≥3 and/or pT3 at radical prostatectomy in 96% of pN+ cases. A median of seven additional blocks (1–28) was required for complete tissue embedding. Our findings indicate that submission of the entire fat can optimise PLND assessment but has a significant impact on laboratory workload. Complete submission of selected high-risk cases may be a reasonable alternative.

Handling and reporting of pelvic lymphadenectomy specimens in prostate and bladder cancer: a web-based survey by the European Network of Uropathology

AIMS

Pathological evaluation of lymphadenectomy specimens plays a pivotal role in accurate lymph node (LN) staging. Guidelines standardising the gross handling and reporting of pelvic LN dissection (PLND) in prostate (PCa) and bladder (BCa) cancer are currently lacking. This study aimed to establish current practice patterns of PLND evaluation among pathologists.

METHODS AND RESULTS

A web-based survey was circulated to all members of the European Network of Uropathology (ENUP), comprising 29 questions focusing on the macroscopic handling, LN enumeration and reporting of PLND in PCa and BCa. Two hundred and eighty responses were received from pathologists throughout 23 countries. Only LNs palpable at grossing were submitted by 58%, while 39% routinely embedded the entire specimen. Average LN yield from PLND was ≥10 LNs in 56% and <10 LNs in 44%. Serial section(s) and immunohistochemistry were routinely performed on LN blocks by 42% and <1% of respondents, respectively. To designate a LN microscopically, 91% required a capsule/subcapsular sinus. In pN+ cases, 72% reported the size of the largest metastatic deposit and 94% reported extranodal extension. Isolated tumour cells were interpreted as pN1 by 77%. Deposits identified in fat without associated lymphoid tissue were reported as tumour deposits (pN0) by 36% and replaced LNs (pN+) by 27%. LNs identified in periprostatic fat were included in the PLND LN count by 69%.

CONCLUSION

This study highlights variations in practice with respect to the gross sampling and microscopic evaluation of PLND in urological malignancies. A consensus protocol may provide a framework for more consistent and standardised reporting of PLND specimens.

Detection of CK19 mRNA Using One-step Nucleic Acid Amplification (OSNA) in Prostate Cancer: Preliminary Results

Background: Accurate histopathological evaluation of lymph nodes (LNs) is essential for reliable staging in prostate cancer. In routine practice, conventional techniques only examine parts of the LN. Molecular nodal staging methods are limited by their high costs and extensive time requirement. One-step nucleic acid amplification (OSNA) determines the metastatic status of the complete LN and allows for rapid intraoperative detection of LN metastases. OSNA has been proposed for diagnosis of LN metastases from breast cancer by quantifying the CK19 mRNA copy number. To provide basic data for OSNA development for prostate cancer, we conducted an investigation of CK19 and OSNA in prostate cancer specimens.

Methods: OSNA is based on a short homogenization step and subsequent automated amplification of CK19 mRNA directly from the sample lysate, with results available in 30-40 min. A total of 20 prostate cancer specimens from consecutive patients with intermediate or high-risk prostate cancer (Gleason-Score ≥7) were investigated by both OSNA and conventional histopathology (H&E staining, CK19 immunohistochemistry). OSNA was performed on frozen samples using a ready-to-use amplification kit in an automated real-time detection system. Samples were defined as 'negative' or 'positive' according to mRNA copy number: >5000 copies/µl (++), 250-5000 copies/µl (+), and <250 copies/µl (-).

Results: Histopathological analysis confirmed prostate cancer in all samples: Gleason score 7 (n=11), Gleason score 8 (n=2), and Gleason score 9 (n=6). Gleason score could not be given for one patient who previously underwent hormonal treatment. OSNA analysis detected CK19 expression in 100% of the specimens and high numbers of CK19 mRNA copies in all cases (9 samples ++; 11 samples +). Immunohistochemistry confirmed CK19 expression in 19 of 20 cases. In the immunohistochemistry CK19-negative patient, a Gleason score 9 prostate cancer was diagnosed.

Conclusions: This is the first study using OSNA to detect CK19 expression in prostate cancer. Initial data indicate that this rapid method for molecular LN staging reliably identifies CK19 mRNA in prostate cancer. These results suggest that the OSNA assay may be suitable to improve (intraoperative) LN staging in prostate cancer. For further verification, OSNA analysis of LN specimens from prostate cancer patients is required.

Impact of prostatic anterior fat pads with lymph node staging in prostate cancer

Background: Several reports have revealed the presence of lymph nodes in the prostatic anterior fat pad (PAFP). To date, no study has described the characteristics of Taiwanese patients harboring PAFP lymph nodes with metastatic prostate cancer involvement.

Method: Between December 2006 and May 2015, a total of 849 consecutive patients underwent robot-assisted laparoscopic radical prostatectomy with PAFP dissection. Pathological examination of the dissected PAFP was conducted to assess the presence of lymphoid tissue and prostate cancer involvement.

Results: Of the 849 patients, 76 (9.0%) had 1-3 PAFP lymph nodes. Moreover, 11 (1.3%) of the 76 patients had positive lymph node metastases of prostate cancer in the PAFP; 5 (0.6%) of the 11 patients, who had negative pelvic lymph node involvement, were upstaged because of positive metastases in PAFP lymph nodes. Among the 76 patients having PAFP lymph nodes, metastatic lymph nodes were associated with the clinical T stage, preoperative Gleason score, pathological T stage, and pathological N stage (p < 0.001). Patients with pathological seminal vesicle invasion and a higher surgical Gleason score also exhibited PAFP lymph node metastases (p < 0.005).

Conclusion: Our data show that 9.0% of patients had PAFP lymph nodes and that 1.3% had prostate cancer metastases. Additionally, 0.6% of patients were upstaged because of positive metastases in PAFP lymph nodes. Because of the pathological analysis of the PAFP, a few patients were upstaged. Thus, routine pathological analysis of the PAFP should only be conducted for those with higher preoperative prostate-specific antigen, higher Gleason score, and advanced T stage observations.

The Application of Gene Expression Profiling in Predictions of Occult Lymph Node Metastasis in Colorectal Cancer Patients

A key factor in determining the likely outcome for a patient with colorectal cancer is whether or not the tumour has metastasised to the lymph nodes-information which is also important in assessing any possibilities of lymph node resection so as to improve survival. In this review we perform a wide-range assessment of literature relating to recent developments in gene expression profiling (GEP) of the primary tumour, to determine their utility in assessing node status. A set of characteristic genes seems to be involved in the prediction of lymph node metastasis (LNM) in colorectal patients. Hence, GEP is applicable in personalised/individualised/tailored therapies and provides insights into developing novel therapeutic targets. Not only is GEP useful in prediction of LNM, but it also allows classification based on differences such as sample size, target gene expression, and examination method.