Lymph node dissection during radical cystectomy for bladder cancer treatment: considerations on relevance and extent

Bladder Cancer: Immunotherapy and Pelvic Lymph Node Dissection

Bladder cancer, a common malignancy of the urinary system, is routinely treated with radiation, chemotherapy, and surgical excision. However, these strategies have inherent limitations and may also result in various side effects. Immunotherapy has garnered considerable attention in recent years as a novel therapeutic approach. It harnesses and activates the patient's immune system to recognize and eliminate cancer cells, which not only prolongs therapeutic efficacy but also minimizes the toxic side effects. Several immune checkpoint inhibitors and cancer vaccines have been developed for the treatment of bladder cancer. Whereas blocking immune checkpoints on the surface of tumor cells augments the effect of immune cells, immunization with tumor-specific antigens can elicit the production of anti-tumor immune effector cells. However, there are several challenges in applying immunotherapy against bladder cancer. For instance, the efficacy of immunotherapy varies considerably across individual patients, and only a small percentage of cancer patients are responsive. Therefore, it is crucial to identify biomarkers that can predict the efficacy of immunotherapy. Pelvic lymph nodes are routinely dissected from bladder cancer patients during surgical intervention in order to remove any metastatic tumor cells. However, some studies indicate that pelvic lymph node dissection may reduce the efficacy of immunotherapy by damaging the immune cells. Therefore, the decision to undertake pelvic lymph node removal should be incumbent on the clinical characteristics of individual patients. Thus, although immunotherapy has the advantages of lower toxic side effects and long-lasting efficacy, its application in bladder cancer still faces challenges, such as the lack of predictive biomarkers and the effects of pelvic lymph node dissection. Further research is needed to explore these issues in order to improve the efficacy of immunotherapy for bladder cancer.

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.

Pelvic lymph node dissection during radical cystectomy for muscle-invasive bladder cancer

Radical cystectomy is the gold-standard treatment option for muscle-invasive and metastatic bladder cancer. At the time of cystectomy, up to 25% of patients harbour metastatic lymph node deposits. These deposits most frequently occur in the obturator fossa, but can be as proximal as the interaortocaval region. Thus, the use of concurrent pelvic lymph node dissection (PLND) with cystectomy has been increasingly reported. Data from studies including many patients suggest substantial oncological benefit in PLND cohorts versus non-PLND cohorts, irrespective of pathological nodal status. Additionally, PLND provides useful prognostic information, including disease burden, lymph node density, and extracapsular extension of metastatic lymph nodes. Accordingly, the National Comprehensive Cancer Network guidelines advocate the use of PLND during radical cystectomy for muscle-invasive bladder cancer. Despite this recommendation, a lack of consensus exists regarding the optimal PLND template. Comparative series suggest that extended PLND provides improved recurrence-free survival and cancer-specific survival compared with more limited PLND templates. More extensive templates (such as super-extended PLND) provide no additional survival benefit at the potential cost of increased operative time and patient morbidity. In addition to extended PLND templates, increased nodal harvest confers an oncological benefit in patients with node-positive disease or in patients with node-negative disease. Accordingly, recommendations for a minimum nodal yield have been proposed. Despite the growing body of evidence, formal recommendations by oncological and urological authoritative bodies have been limited owing to the lack of randomized data and level I evidence.

The current role of circulating biomarkers in non-muscle invasive bladder cancer

Non-muscle invasive bladder cancer (NMIBC) is characterized by its high rate of disease recurrence and relevant disease progression rates. Up to today clinical models are insufficiently predicting outcomes for reliable patient counseling and treatment decision-making. This particularly is a serious problem in patients with high-risk NMIBC who are at high risk for failure of local treatment and thus candidates for early radical cystectomy or even systemic (neoadjuvant) chemotherapy. Next to its clinical variability, bladder cancer is genetically a highly heterogeneous disease. There is an essential need of biomarkers for improving clinical staging, real-time monitoring of disease with or without active treatment, as well as improved outcome prognostication. Liquid biopsies of circulating biomarkers in the blood and urine are promising non-invasive diagnostics that hold the potential facilitating these needs. In this review we report the latest data and evidence on cell-free circulating tumor desoxyribonucleic acid (ctDNA) and circulating tumor cells (CTC) in NMIBC. We summarize their current status in clinical diagnostics, discuss limitations and address future needs.

The current status and clinical value of circulating tumor cells and circulating cell-free tumor DNA in bladder cancer

Urothelial carcinoma of the bladder (UCB) is a complex disease, which is associated with highly aggressive tumor biologic behavior, especially in patients with muscle-invasive and advanced tumors. Despite multimodal therapy options including surgery, radiotherapy and chemotherapy, UCB patients frequently suffer from poor clinical outcome. Indeed, the potential of diverse opportunities for modern targeted therapies is not sufficiently elucidated in UCB yet. To improve the suboptimal treatment situation in UCB, biomarkers are urgently needed that help detecting minimal residual disease (MRD), predicting therapy response and subsequently prognosis as well as enabling patient stratification for further therapies and therapy monitoring, respectively. To date, decision making regarding treatment planning is mainly based on histopathologic evaluation of biopsies predominantly derived from the primary tumors and on clinical staging. However, both methods are imperfect for sufficient outcome prediction. During disease progression, individual disseminated tumor cells and consecutively metastases can acquire characteristics that do not match those of the corresponding primary tumors, and often are only hardly assessable for further evaluation. Therefore, during recent years, strong efforts were directed to establish non-invasive biomarkers from liquid biopsies. Urine cytology and serum tumor markers have been established for diagnostic purposes, but are still insufficient as universal biomarkers for decision-making and treatment of UCB patients. To date, the clinical relevance of various newly established blood-based biomarkers comprising circulating tumor cells (CTCs), circulating cell-free nucleic acids or tumor-educated platelets is being tested in cancer patients. In this review we summarize the current state and clinical application of CTCs and circulating cell-free tumor DNA originating from blood as biomarkers in patients with different UCB stages.

Do circulating tumor cells have a role in deciding on adjuvant chemotherapy after radical cystectomy?

Radical cystectomy (RC) with bilateral pelvic lymphadenectomy with or without perioperative chemotherapy is the golden standard treatment in muscle invasive and recurrent high-grade non-muscle invasive urothelial carcinoma of the bladder (UCB). Despite treatment with curative intent, up to 50% of patients develop metastasis and die from UCB due to micro-metastatic disease undetectable for current staging techniques prior to definitive therapy. Tumor cell dissemination is a crucial step in the natural history of the metastatic cascade. Circulating tumor cells (CTC) are malignant epithelial cells detectable in the peripheral blood of patients with various malignancies. In UCB, CTC are detectable in a significant number of patients prior to RC and associated with inferior outcomes. In this review, we summarize the current literature regarding CTC in UCB, discussing their potential on clinical decision-making regarding multimodal treatment and implications on the application of novel targeted therapies in the future. There is reliable evidence that presence of CTC in clinically non-metastatic UCB patients treated with RC are a powerful predictor for unfavorable outcomes and may be useful for adjuvant chemotherapy decision-making and monitoring. However, currently, the evidence is limited, and thus, integration of CTC in future UCB clinical trials is strongly recommended to shed more light on the potential of this promising biomarker.

PET/CT versus conventional CT for detection of lymph node metastases in patients with locally advanced bladder cancer

Background

We studied patients treated with radical cystectomy for locally advanced bladder cancer to compare the results of both preoperative positron emission tomography/computed tomography (PET/CT) and conventional CT with the findings of postoperative histopathological evaluation of lymph nodes.

Methods

Patients who had bladder cancer and were candidates for cystectomy underwent preoperative PET/CT using 18-fluorodeoxyglucose (FDG) and conventional CT. The results regarding lymph node involvement were independently evaluated by two experienced radiologists and were subsequently compared with histopathology results, the latter of which were reassessed by an experienced uropathologist (HO).

Results

There were 54 evaluable patients (mean age 68 years, 47 [85 %] males and 7 [15 %] females) with pT and pN status as follows: < pT2-14 (26 %), pT2-10 (18 %), and > pT2-30 (56 %); pN0 37 (69 %) and pN+ 17 (31 %). PET/CT showed positive lymph nodes in 12 patients (22 %), and 7 of those cases were confirmed by histopathology; the corresponding results for conventional CT were 11 (20 %) and 7 patients (13 %), respectively. PET/CT had 41 % sensitivity, 86 % specificity, 58 % PPV, and 76 % NPV, whereas the corresponding figures for conventional CT were 41 %, 89 %, 64 %, and 77 %. Additional analyses of the right and left side of the body or in specified anatomical regions gave similar results.

Conclusions

In this study, PET/CT and conventional CT had similar low sensitivity in detecting and localizing regional lymph node metastasis in bladder cancer.