The role of lymph node density in bladder cancer prognostication

Development and external validation of nomograms predicting disease-free and cancer-specific survival after radical cystectomy

PURPOSE

To develop two nomograms predicting disease-free survival (DFS) and cancer-specific survival (CSS) and to externally validate them in multiple series.

METHODS

Prospectively collected data from a single-centre series of 818 consecutive patients who underwent RC and PLND were used to build the nomogram. External validation was performed in 3,173 patients from 7 centres worldwide. Time to recurrence and to cancer-specific death were addressed with univariable and multivariable analyses. Nomograms were built to predict 2-, 5- and 8-year DFS and CSS probabilities. Predictive accuracy was quantified using the concordance index.

RESULTS

Age, pathologic T stage, lymph-node density and extent of PLND were independent predictors of DFS and CSS (p < 0.05). Discrimination accuracies for DFS and CSS at 2, 5 and 8 years were 0.81, 0.8, 0.79 and 0.82, 0.81, 0.8, respectively, with a slight overestimation at calibration plots beyond 24 months. In the external series, predictive accuracies for DFS and CSS at 2, 5 and 8 years were 0.83, 0.82, 0.82 and 0.85, 0.85, 0.83 for European centres; 0.73, 0.72, 0.71 and 0.80, 0.74, 0.68 for African series; 0.76, 0.74, 0.71 and 0.79, 0.76, 0.73 for American series.

CONCLUSIONS

These nomograms developed from a contemporary series are simple clinical tools and provide optimal oncologic outcome prediction in all external cohorts.

Seeking a standard for adequate pathologic lymph node staging in primary bladder carcinoma

The purposes of this study are to evaluate the adequacy of pathologic lymph node (LN) staging in radical cystectomy specimens from patients with urothelial carcinoma of the bladder and to analyze the frequency of LN metastases among different anatomic regions. All radical cystectomies performed for primary urothelial bladder cancer over a 5-year period (January 2007-September 2012) at a single institution were reviewed. Particular attention was paid to the total number of LNs examined, the number and location of LNs with metastases (positive LNs), and the presence or absence of extranodal tumor extension and/or lymphovascular invasion in the cystectomy specimen. Results and data were analyzed with Origin 6.0 and Microsoft Office Excel 2007 software. A total of 248 radical cystectomies with 8,432 LNs were reviewed. A total of 60 (24 %) cases, with 274 positive LNs out of the 1,982 total (13.8 %), were identified with a male to female ratio of 6.5:1 (52 male, 8 female patients). The average number of LNs examined in each case was 33.0 ± 20.9 (range 5-112). The average number of positive LNs identified in each case was 4.5 ± 4.8 (range 1-26). Among all of the LNs, the hypogastric/obturator (internal iliac) LNs were the most commonly submitted (35.2 %) and also yielded the highest number of positive LNs (46.0 %). On average, for cases staged pN1 and pN2, there was one positive LN per 17.8 and 8.9 LNs examined from the primary drainage LNs, respectively. For pN3 cases, one out of 4.4 secondary drainage LNs was found to be positive. Similarly, one out of 4.0 distant LNs was found to be positive in cases with pM1 staging. Our study suggests that, on average, 23 LNs (including 18 primary drainage LNs and five secondary drainage LNs) should be submitted for optimal pN staging. For adequate pM1 staging, an average of four distal LNs should be evaluated. In total, an average of 27 LNs (23 for pN staging and 4 for pM staging) should be examined in radical cystectomy specimens. We also propose to stratify the number of positive LNs according to the drainage area.

Differences in histopathological evaluation of standard lymph node dissections result in differences in nodal count but not in survival

OBJECTIVE

To analyse whether the reported differences in nodal yield at pelvic lymph node dissection (PLND) for bladder cancer, between two hospitals, are reflected in the survival rates.

PATIENTS AND METHODS

We assessed follow-up data of all 174 patients (mean age: 62.7, median follow-up: 3 years) who underwent PLND between 1 January 2007 and 31 December 2009 at two different hospitals. PLND was performed according to a standardized template by the same urologists for comparable bladder cancer patients. Mean number of reported lymph nodes was 16 at hospital A versus 28 at hospital B. We compared the overall survival (OS), disease-specific survival (DSS) and recurrence-free survival (RFS) between both cohorts and performed a multivariate analysis.

RESULTS

The cumulative probability for 2-year OS, DSS and RFS for hospital A are 61, 64 and 54 %, versus 58, 58 and 53 % for hospital B, respectively. Kaplan-Meier survival curves did not reveal statistically significant differences between both groups (OS: p log-rank = 0.75, DSS: p log-rank = 0.56, and RFS: p log-rank = 0.80). Also after adjustment for pT stage and neoadjuvant chemotherapy, survival was not significantly different between hospital A and hospital B.

CONCLUSION

Despite differences in lymph node yield in PLND specimens, this study reveals no significant differences in survival outcomes between both hospitals. Standardized histopathological methods should be agreed upon by pathologists before integrating nodal yield and subsequent lymph node density as indicators of the quality of surgery and as prognostic factors.

[Lymphadenectomy for bladder cancer: current status and controversies]

Pelvic lymph node dissection is an integral part of the radical cystectomy procedure for patients with muscle-invasive bladder cancer. The optimal extent of the lymphadenectomy (LND) and mainly the proximal template boundary remain controversial issues. In view of the existing mapping studies and retrospective analyses, extended LND up to the mid-upper third of the common iliac vessels appears to provide further prognostic and therapeutic benefit and therefore should be defined as standard LND. This applies for all procedures irrespective of the choice of surgical approach (open surgery, minimally invasive approach). In this context total lymph node count is not a quality criterion because nodal yield is overly influenced by the individual patient's anatomy, surgical technique, template applied and pathological work-up. Consecutively, considerable inter-institutional differences result, which render any comparison impossible. Lymph node density is thought to be a superior prognostic factor, but it is similarly influenced by the above-mentioned factors. Concerning molecular techniques to improve the sensitivity of postoperative nodal staging further research is necessary. The two ongoing prospective randomized trials will potentially help to further define the optimal LND template.

Identifying additional lymph nodes in radical cystectomy lymphadenectomy specimens

Lymph node count has prognostic implications in bladder cancer patients who are treated with radical cystectomy. Lymph nodes that are too small to identify grossly can easily be missed, potentially leading to missed nodal metastases and inaccurate nodal counts, resulting in inaccurate prognoses. We investigated whether there is a benefit to submitting the entire lymph node packet for histological examination to identify additional lymph nodes. We prospectively assessed 61 pelvic lymphadenectomy specimens in 14 consecutive patients undergoing radical cystectomy. The specimens were placed in Carnoy's solution overnight, then analyzed for lymph nodes. The residual tissue was entirely submitted to assess for additional lymph nodes. In 61 specimens, we identified 391 lymph nodes, ranging from 4-44 nodes per patient. We identified 238 (61%) lymph nodes with standard techniques and 153 (39%) lymph nodes in submitted residual tissue. The number of additional lymph nodes found in the residual tissue ranged from 0 to 26 (0-75%) per patient. These lymph nodes ranged in size from 0.05 to 1 cm. All additional lymph nodes were negative for metastatic disease. Submitting the entire specimen for histological examination allowed for identification of more lymph nodes in radical cystectomy pelvic lymphadenectomy specimens. However, as none of the additional lymph nodes contained metastatic disease, it is unclear if there is a clinical benefit in evaluating lymph nodes that are neither visible nor palpable in lymphadenectomy specimens.

Pelvic lymphadenectomy in the treatment of invasive bladder cancer: literature review

The standard surgical treatment of invasive bladder cancer is the radical cystectomy and pelvic lymph node dissection (PLND). Up to one-third of patients with invasive bladder cancer have lymph node metastasis. Thus, PLND has important therapeutic and prognostic benefits. The number of lymph nodes that should be removed and the extent of the PLND are still a controversial issue. Recently, the trend of PLND increased toward more extended PLND. Several prognostic factors related to PLND were reported in the literature. In this paper, we will discuss the different PLND templates, number of lymph nodes that should be resected, lymph node density, lymphovascular invasion, tumor burden, extracapsular extension, and the aggregate lymph node metastasis diameter.

A prospective randomized trial for postoperative vs. preoperative adjuvant radiotherapy for muscle-invasive bladder cancer

PURPOSE

Although radical cystectomy is considered to be the primary treatment for muscle-invasive bladder cancer, it is associated with unfavorable outcome. Local recurrence is still a major problem. Survival rates as well as quality of live are far from being satisfactory. Postoperative radiotherapy is considered the standard adjuvant treatment in the NCI-Egypt. This is a prospective randomized study conducted to compare preoperative with postoperative radiotherapy as regard the survival and complication rates.

PATIENTS AND METHODS

In the period from May, 2004 to June 2007, 100 eligible patients were included into the study, 50 patients in each treatment arm. Pelvic irradiation was identical in both groups aiming at 50 Gy/25 Fs/5 wk. Radical cystectomy was the standard surgery. Locoregional control, survival rates, and complications rates were compared in both arms.

RESULTS

Patients had a median follow-up period of 32 months (range 0-69 months). Patients had an average age of 54.8 ± 9.5 years with a male/female ratio 3:1. In the present study, transitional cell carcinoma constitutes (51%), while squamous cell carcinoma was reported in 46% of cases. Grades II and III pathology were 81% and 17%, respectively. Pathological stage P2b was encountered in 39.5% of the patients followed by P3b (33.3%) and P3a (14.6%). For the preoperative group, the 3-year overall survival, disease-free survival, locoregional control, and metastases-free survival rates were 53.4%, 47.4%, 89.3%, and 61.5%, respectively. The corresponding figures for the postoperative group were 51.8%, 34.1%, 80.6%, and 55.7% for the postoperative group. None of the patients had serious radiation reactions.

CONCLUSION

In our study, preoperative radiotherapy was almost equivalent to postoperative radiation therapy as regard OS, DFS, as well as complication rates. Given the recent physical developments in radiation therapy techniques and the biological rationale for treating the pelvis after cystectomy, adjuvant radiotherapy should be re-evaluated world wide. Preoperative radiotherapy may re-emerge as a useful tool for adjuvant treatment.

Lymph node density affects cancer-specific survival in patients with lymph node-positive urothelial bladder cancer following radical cystectomy

BACKGROUND

The prognosis for patients with lymph node (LN)-positive bladder cancer (BCa) is likely affected by the extent of lymphadenectomy in radical cystectomy (RC) cases. Specifically, the prognostic significance of the LN density (ratio of positive LNs to the total number removed) has been demonstrated.

OBJECTIVE

To evaluate the prognostic signature of lymphadenectomy variables, including the LN density, for a large, multicentre cohort of RC patients with LN-positive BCa.

DESIGN, SETTING, AND PARTICIPANTS

The clinical and histopathologic data from 477 patients with LN-positive urothelial BCa (pN1-2) were analysed. The median follow-up period for all living patients was 28 mo.

MEASUREMENTS

Multivariable Cox regression analysis was used to test the effect of various pelvic lymph node dissection (PLND) variables on cancer-specific survival (CSS) based on colinearity in various models.

RESULTS AND LIMITATIONS

The median number of LNs removed was 12 (range: 1-66), and the median number of positive LNs was 2 (range: 1-25). Two hundred ninety (60.8%) of the patients presented with stage pN2 disease. The median and mean LN density was 17.6% and 29% (range: 2.3-100), respectively, where 268 (56.2%) and 209 (43.8%) patients exhibited am LN density of ≤20% and >20%, respectively. In separate multivariable Cox regression models adjusted for age, sex, pTN stage, grade, associated Tis, and adjuvant chemotherapy, the interval-scaled LN density (hazard ratio [HR]: 1.01; p=0.002) and the LN density, ordinal-scaled by 20% (HR: 1.65; p<0.001) exhibit independent effects on CSS. In addition, an independent contribution appears from the pT but not the pN stage. Limitations include surgeon selection bias when determining the extent of lymphadenectomy.

CONCLUSIONS

Our results support the prognostic relevance of LN density in patients with LN-positive BCa, where a threshold value of 20% stratifies the population into two prognostically distinct groups. Before LN density is integrated into the clinical decision-making process, these results should be validated by prospective studies with defined LN templates and standardised histopathologic methods.

Adjuvant and neoadjuvant radiotherapy for bladder cancer: revisited

To date, radical cystectomy has continued to be the treatment of choice for muscle-invasive bladder cancer. It is associated with a 5-year disease-free survival rate ranging from 27–55%. This outcome is significantly worse when reporting upon locally advanced cases. The independent prognostic factors include: tumor stage, grade, pelvic nodal involvement and some other additional factors. Beside the higher reported incidence of distant metastasis, local recurrence either alone or combined with systemic relapse has been shown to be experienced by 23–50% of locally advanced patients – a rate that was much more frequent than previously believed. Nonrandomized trials of preoperative radiotherapy have suggested improved survival rates. However, only one out of the six randomized preoperative trials in the literature published in English has proved to be significant. On the other hand, the only randomized trial and most retrospective studies dealing with postoperative radiotherapy revealed a significant increase in disease-free survival. Late complications of post operative radiotherapy, contrary to former belief, were acceptable and generally depended upon the volume of the irradiated normal tissues and the radiotherapy techniques used. Most of these adjuvant or neoadjuvant reports were performed in the 1970s and 1980s using conventional radiation techniques. Modern radiotherapy, delivering higher doses to the tumor while saving a significant amount of the surrounding normal structure, has not been rigorously tested. However, these techniques have already succeeded in improving treatment end results in other pelvic tumors.