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

Pelvic lymphadenectomy: Evaluating nodal stage migration and will rogers effect in bladder cancer

INTRODUCTION

Pelvic lymphadenectomy (PLND) alongside radical cystectomy (RC), provides crucial diagnostic and therapeutic value in patients with bladder cancer. With the advent of neoadjuvant chemotherapy and prospective data supporting standard PLND, controversy remains regarding the optimal PLND extent and patient selection. Nearly 40% of patients may not receive adequate PLND, even though 25% of patients have positive lymph nodes (LN) at time of RC. We hypothesized that PLND still remains an important facet of bladder cancer treatment. To clarify the prognostic importance of nodal yield, we performed a retrospective investigation of a heterogenous population (pTanyNx/0M0) of patients undergoing RC.

METHODS

From the Surveillance, Epidemiology, and End Results (SEER) program, we identified pTanyNx/0M0 bladder cancer patients undergoing RC from 2004 to 2015. Kaplan Meier curves and Cox proportional hazards models assessed cancer-specific survival. Patients were analyzed with PLND performed as the primary covariate. Survival analysis then stratified patients undergoing PLND by LN yield, both as a continuous and categorial variable (≤10, 11-20, 21-30, and >30), and T stage.

RESULTS

The final cohort included pTanyNx/0M0 patients with urothelial bladder cancer (n = 12,096); median follow up was 39 (IQR: 17-77) months. PLND was performed in 81.45% of patients with a median LN yield of 14 (IQR: 7-23). Most commonly, patients had T2 disease (44.68%). After controlling for age and T stage, patients receiving PLND had improved CSS (HR = 0.56, [95% CI: 0.51-0.62]) compared to those that did not receive PLND. When grouping patients by LN yield, survival improved in a "dose dependent" manner (>30 LN: HR = 0.76, [95% CI: 0.66-0.87]). We noted similar results when stratifying patients into non-muscle-invasive (NMIBC) and muscle-invasive bladder cancer (MIBC).

CONCLUSIONS

In a large contemporary series of pTanyNx/0M0 bladder cancer patients, we found a significant oncologic benefit to PLND. Higher LN yield correlated to improved CSS in non-muscle-invasive and muscle-invasive disease. Our data support the possibility of occult micrometastasis even in non-muscle-invasive disease. Additionally, in light of recent advances in adjuvant immunotherapy, our results emphasize the importance of adequate nodal yield for accurate staging and optimal treatment.

The Phenomenon of "Therapeutic" Nodal Yield at Cystectomy for Bladder Cancer: Do Not Discount the Will Rogers Effect

While multiple mechanisms have been hypothesized to explain the therapeutic effect of lymph node (LN) yield in patients with urothelial cell carcinoma (UCC) undergoing radical cystectomy (RC), the effect of stage migration, commonly known as the Will Rogers effect, is often discounted. We reviewed the National Cancer Database for patients with UCC undergoing RC with pathologically node-negative (pN0) disease from 2004 to 2016. We tested for an adjusted association between LN yield and overall survival using multivariable Cox proportional-hazard models. Median survival was estimated using the Kaplan-Meier method. We identified 19 939 patients with pN0 UCC treated with RC. After adjustment, patients in the highest quantile for LN yield (≥26 LNs) had a 34% lower risk of death in comparison to patients in the lowest quantile (≤5 LNs). As we increased the threshold for LN yield for dichotomization from >5 to >15 to >25 LNs, median survival increased from 83 to 95 to 103 mo. The pN0 group with higher LN yield appeared to live longer in this analysis owing to the mathematical artifact of how patients are indexed. Resection of a greater number of negative LNs will lead to higher fidelity for pN0 cohorts being evaluated, as the likelihood of contamination by pN+ cases that were missed will be lower.

Patient summary

A strategy to dissect a high number of lymph nodes in patients undergoing removal of their bladder for bladder cancer can be associated with side effects, and the benefit in terms of cancer control or survival remains uncertain. Urologists and their patients should engage in shared decision-making and consider the risks and benefits of more extensive lymph node dissection during surgery.

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.

The role of 18F-FDG PET/CT scan compared to CT-scan alone for lymph node staging before radical cystectomy in patients with bladder cancer

BACKGROUND

Accurate Lymph node (LN) staging before radical cystectomy (RC) in patients with bladder cancer (BC) is crucial to improve patient's management. 18F-fluorodeoxyglucose positron-emission tomography-computed tomography (FDG-PET-CT) become widely used in the loco-regional staging of BC. The diagnostic performance of PET-CT in preoperative LN staging of BC is still unknown due to lacking large trials.

OBJECTIVES

We aim to evaluate the diagnostic value of PET-CT scan, compared with CT scan alone for preoperative LN staging of BC.

PATIENTS AND METHODS

From January 2010 to November 2020, we retrospectively reviewed the records of 300 patients undergoing RC for muscle-invasive BC and high-risk non-muscle-invasive BC. All patients had PET-CT and CT of abdomen and pelvis to assess for pelvic LN metastases before RC. Patients were excluded from analysis if they had neoadjuvant chemotherapy (NAC). Sensitivity, specificity, and accuracy for detecting pelvic LN metastases were determined by comparing the results of the FDG PET-CT and CT alone to the final histopathology reports obtained after RC.

RESULTS

LN metastasis was confirmed histology in 134 patients (44.7%). On a patient-based analysis, PET-CT, and CT showed a sensitivity of 40.3% and 13.4 %, respectively, a specificity of 79.5% and 86.7 %, respectively, positive predictive value (PPV) of 61.4% and 45%, respectively, and negative predictive value (NPV) of 62.3% and 55.4%, respectively. The diagnostic accuracy of PET-CT scan depends on multiple preoperative and postoperative factors.

CONCLUSION

PET-CT is more accurate than CT-scan alone for preoperative LN staging in patients with BC.