Lymph node density predicts recurrence and death after inguinal lymph node dissection for penile cancer

Updates in staging of penile cancer: the evolution, nuances, and issues

Staging based on the tumor (T), node (N), and metastasis (M) schema of the American Joint Committee on Cancer (AJCC) is usually the most important prognostic factor for any tumor type. Although a rare tumor, in penile cancers, this staging has evolved rapidly in the last two editions of the AJCC Cancer Staging manuals. These changes and updates are largely based on the advancement in our knowledge of the complex anatomy of the penis, the role of histopathological variables in disease biology, and the results of multicentric studies comprising large data sets. In this review, we present the evolution of the AJCC staging model from its inception to the present day. The evidence and data that entailed these changes are also discussed. We highlight a few issues with the current staging model and also briefly discuss the future perspectives and the road map which, with the help of global efforts, can further refine the staging models.

“Light green up”: Indocyanine Green Fluorescence Imaging–guided Robotic Bilateral Inguinal Lymphadenectomy by the Hypogastric Subcutaneous Approach for Penile Cancer

Background

Inguinal lymphadenectomy is of great significance in the management of penile cancer, which aims to mitigate the progression of lymph node metastasis. It is important to improve the efficiency of lymph node dissection and reduce surgical complications.

Objective

To detail a novel technique for robotic bilateral inguinal lymphadenectomy through the hypogastric subcutaneous approach by indocyanine green (ICG) fluorescence imaging, which promotes the identification and dissection of inguinal lymph nodes with considerable safety.

Design, setting, and participants

Ten eligible penile cancer patients who underwent ICG fluorescence imaging–guided robotic bilateral inguinal lymphadenectomy were prospectively enrolled (ICG group). Sixteen patients who underwent the surgery without ICG were retrospectively set as the control (non-ICG) group. Follow-up records for at least 12 mo were required.

Surgical procedure

Inguinal lymphadenectomy was performed by the hypogastric subcutaneous approach. The ICG solution was subcutaneously injected into the prepuce at the beginning of surgery, and ICG fluorescence imaging–guided robotic-assisted bilateral inguinal lymphadenectomy was conducted.

Measurements

Clinical outcomes were collected. The primary study outcome measurement was the number of dissected inguinal lymph nodes.

Results and limitations

The numbers of inguinal overall, superficial, and deep lymph nodes retrieved were all higher in the ICG than in the non-ICG group (p < 0.05). No patients had severe perioperative complications. No difference was found in the overall complication rate and 12-mo survival between two groups (p > 0.05).

Conclusions

ICG fluorescence imaging–guided robotic inguinal lymphadenectomy via the hypogastric subcutaneous approach is feasible and safe for patients with penile cancer, which is beneficial for dissecting more inguinal lymph nodes with few surgical complications.

Patient summary

We developed a promising indocyanine green fluorescence imaging–guided technique to perform robotic bilateral inguinal lymphadenectomy on patients with penile cancer, which conduces to remove more inguinal lymph nodes with limited complications.

The prognostic value of lymph node ratio in comparison to positive lymph node count in penile squamous cell carcinoma

PURPOSE

Penile cancer is a rare male neoplasm with a wide variation in its global incidence. In this study, the prognostic value of lymph node ratio (LNR) was compared to that of positive lymph node count (PLNC) in penile squamous cell carcinoma.

METHODS

A total of 249 patients with penile squamous cell carcinoma were enrolled from The Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2015. The X-tile program was used to calculate the optimal cut-off values of LNR and PLNC that discriminate survival. We used the χ2 or the Fisher exact probability test to assess the association between clinical-pathological characteristics and LNR or PLNC. Univariate and multivariate Cox regression analyses were performed to identify independent prognostic factors for survival. Spearman correlation analysis was used to determine the correlation between LNR and PLNC.

RESULTS

We found that patients with high LNR tended to have advanced N stage, the 7th AJCC stage, and higher pathological grade, while patients with high PLNC had advanced N stage and the 7th AJCC stage. Univariate Cox regression analysis revealed that the N stage, M stage, the 7th AJCC stage, lymph-vascular invasion, LNR, and PLNC were significantly associated with prognosis. Multivariate Cox regression analysis demonstrated that LNR rather than PLNC was an independent prognostic factor for cancer-specific survival. Subgroup analysis of node-positive patients showed that LNR was associated with CSS, while PLNC was not.

CONCLUSION

LNR was a better predictor for long-term prognosis than PLNC in patients with penile squamous cell carcinoma.

Inguinal lymph node density as a powerful predictor of cancer specific survival in patients with node-positive penile cancer

INTRODUCTION

Penile cancer (PC) is an aggressive malignancy in which the most important prognostic factor for cancer specific survival (CSS) is the involvement of regional lymph nodes (LNs). Lymph node density (LND) could become a superior prognostic tool for CSS, by accounting for both extent of dissection and nodal disease burden. We aim to validate LND as a prognostic factor for CSS in a contemporary series of patients with PC treated and followed at a single high-volume center, treating more than 25 PC patients per year, over a 13-year period.

METHODS

Clinical charts of all patients with PC who underwent surgical treatment between 2007 and 2020 were reviewed. Clinicopathological data was collected and analyzed retrospectively. We only included patients with ≥ 8 LNs removed in a unilateral ILND or ≥16 LNs when a bilateral approach was used. We attempted to find an optimal threshold for LND, capable of maximizing effect difference in terms of CSS and RFS between dichotomized groups. To determine this threshold, we used the chi-squared and the Mann-Whitney tests, and it was required to fulfill the proportional hazards assumption. We assessed different thresholds previously reported in the literature. In our study the optimal threshold for LND was determined to be ≤ 20% Descriptive statistics were used to summarize patient characteristics, CSS and RFS were graphically represented by Kaplan-Meier estimates. Harrell's C index for CSS and RFS were calculated for LND and pN stage, to determine which variable has a superior predictive capacity RESULTS: We identified 110 patients with PC who underwent ILND at our institution, of these, 87 were node-positive and were included in the final analysis. Overall estimates of CSS showed a 3-year CSS of 43% (95% CI: 32-54), the estimated 3-year CSS for the patients with a LND ≤ 20% was 69% (95% CI: 50-82) and 26% (95% CI: 14-39) in the group with a LND >20% (Log-rank P = 0.001). The estimated 3-year RFS for the patients with LND ≤ 20% was 61% (95% CI: 42-76) and 30% (95% CI: 16-44) in the group with a LND >20% (Log-rank P = 0.009). The results of univariate analysis indicate that in patients with a LND >20% the risk for cancer specific mortality was increased (HR 2.68; 95% CI: 1.45-4.98, P =  0.002) compared with LND ≤ 20%. In the and Cox multivariate analysis after Adjusting for age and pN stage the association increased (HR 2.73; 95%, CI 1.38-5.40, P = 0.004). Harrell´s C index for CSS was 0.63 for LND vs. 0.54 for pN stage, suggesting a 9% higher concordance for LND and CSS.

CONCLUSIONS

Lymph node density stands as a promising tool for risk-stratifying patients with node-positive PC after ILND. In this retrospective study, LND was a significant predictor of CSS and RFS when using a LND >20% threshold, and also showed a superior predictive ability than pN stage. These results support the use of the LND parameter in clinical practice with a final goal to improve risk stratification, and individualized adjuvant treatment decision-making to patients with high-risk of cancer specific mortality.

Impact of Examined Lymph Node Count and Lymph Node Density on Overall Survival of Penile Cancer

BACKGROUND

Few studies have explored the optimal examined lymph node count and lymph node density cutoff values that could be used to predict the survival of patients with penile cancer. We further clarify the prognostic value of lymph node density and examined lymph node count in penile cancer.

METHODS

The Surveillance, Epidemiology, and End Results (SEER) database was explored to recruit penile cancer patients from 2010 to 2015. A retrospective analysis of penile cancer patients' data from the First Affiliated Hospital of Anhui Medical University was performed for verification (2006-2016). The cutoff values of examined lymph node count and lymph node density were performed according to the ROC curve. Kaplan-Meier survival analysis was used to compare survival differences among different groups. Univariate and multivariate Cox proportional hazard regression analyses were used to determine the significant variables. On the basis of Cox proportional hazards regression model, a nomogram was established and validated by calibration plot diagrams and concordance index (C-index).

RESULTS

A total of 528 patients in the Surveillance, Epidemiology, and End Results cohort and 156 patients in the Chinese cohort were included in this study. Using the ROC curve, we found that the recommended cutoff values of ELN and LND were 13 and 9.3%, respectively (P <0.001). Kaplan-Meier curves suggested the significant differences of overall survival among different examined lymph nodes and lymph node density. Multivariate analysis indicated ELN and LND were independent prognostic factor for OS of penile cancer patients. Nomogram showed the contribution of ELN and LND to predicting OS was large. The C-index at 3-, and 5-year were 0.744 for overall survival (95% CI 0.711-0.777).

CONCLUSIONS

The more lymph nodes examined, the lower the density of lymph nodes, and the higher the long-term survival rate of penile cancer. We recommended 13 examined lymph nodes and lymph node density >9.3% as the cutoff value for evaluating the prognosis of penile cancer patients.

What Is New in the Pathologic Staging of Penile Carcinoma in the 8th Edition of AJCC TNM Model: Rationale for Changes With Practical Stage-by-stage Category Diagnostic Considerations

For >50 years the tumor, node, metastasis (TNM) classification model of malignant tumors has been the main resource for clinicians, pathologists, radiologists and public health professionals ensuring a homogeneous classification and patients' management based on common staging and prognosis factors. Penile cancer was first included for staging in the third edition of the TNM classification with several changes in the last version, the 8th edition of the AJCC TNM Manual, in 2017. Some changes in the pT category were done due to recent knowledge regarding the prognostic importance of anatomical level of invasion, vascular and perineural invasion and tumor grading. These changes must be interpreted in the light of a required understanding of the complex anatomy of penile compartments especially their histological boundaries, the morphological differences of each level needed for the correct classification, the heterogeneity of penile squamous cell carcinomas and an adequate criticism of the current model used by the TNM system. We present here a series of stage-by-stage category diagnostic considerations based on the clinical experience acummulated over the years of applying the different TNM staging classifications in our large clinical practice. Some discrepancies will need well-designed prospective studies for im4proving the actual classification.

Log ODDS (LODDS) of positive lymph nodes as a predictor of overall survival in squamous cell carcinoma of the penis

OBJECTIVE

To evaluate the role of logarithmic ODDS (LODDS) in the number of positive lymph nodes and the number of negative lymph nodes as a prognostic metric in the squamous cell carcinoma (SCC) penis.

METHODS

Data were retrospectively collected from 96 cases of SCC penis that underwent bilateral groin dissection between 2010 and 2015 at our institute. Lymph node density (LND) and LODDS were calculated for all the patients and classified according to American Joint Committee on Cancer (AJCC) pN staging. Thresholds for LND (24% and 46%) and LODDS (-0.75 and 0) were established. Multivariate analysis of various cofactors was done with overall survival (OS) as a dependent factor. Three classification systems were compared using receiver operative characteristic (ROC) curve analysis.

RESULTS

Univariate analysis showed that AJCC pN, LND, and LODDS were all significantly correlated with OS. However, only LODDS (HR, 11.185; p = .023) remained an independent prognostic factor through multivariate analysis. LODDS (log-likelihood = 3832 vs. 3798; p < .001) had better prognostic performance than pN and better discriminatory ability than LND (AIC = 3902 vs. 3928). LODDS had better power of discrimination than LND and pN. LODDS could predict survival in lymph node yield (LNY) < 15 (p < .001).

CONCLUSION

LODDS is an independent predictor of OS in the SCC penis and has superior prognostic significance than the AJCC pN and LND classification systems.

Evolving insights into penile cancer pathology and the eighth edition of the AJCC TNM staging system

The majority of penile malignant tumors are squamous cell carcinomas. They are pathologically defined as epithelial neoplasms originating in the squamous cells of the inner mucosal lining of the glans, coronal sulcus or foreskin. Tumor location and site of origin is preferentially in glans (70%) followed by foreskin (25%) and coronal sulcus (5%). Despite the variable geographic distribution, pathological features of penile carcinomas in areas of high- and low-risk are similar. Penile tumors are morphologically heterogeneous. A major advance, based on biological, etiological and prognostic factors, is the 2016 WHO classification separating epithelial penile neoplasia, precancerous and invasive, in non-HPV and HPV-related.

Neoadjuvant chemotherapy for lymph node-positive penile cancer: current evidence and knowledge

PURPOSE OF REVIEW

To review the latest in penile cancer treatment focusing on neoadjuvant chemotherapy in patients with regional lymph node involvement.

RECENT FINDINGS

Patients with regional lymph node involvement from penile cancer still suffer from a poor prognosis, and the chances to achieve cure are primarily dependent on the extent of the disease. Despite multiple lines of research are indicating the need for a multimodal management of the disease upfront, the search for newer effective systemic therapies is ongoing. The available guidelines currently suggest the use of combination chemotherapy regimens including taxanes and cisplatin as induction therapy before lymphadenectomy in patients with locally advanced disease (i.e., fixed or bulky inguinal lymph nodes or pelvic lymph node involvement). Research in the field will aim to provide more effective systemic therapies also in patients with a more limited disease spread to further improve the outcomes. Data from the literature also indicate the possibility to effectively administer postoperative chemotherapy in selected high-risk patients.

SUMMARY

We aimed to provide the evidence from the literature and the new avenues that would help delineating the optimal therapeutic pathway for these complex patients, commenting on the new opportunities that may come from the ongoing research.

A risk calculator predicting recurrence in lymph node metastatic penile cancer

OBJECTIVES

To develop and externally validate a risk calculator for prediction of any cancer recurrence in patients with penile squamous cell carcinoma (pSCC) and inguinal lymph node metastases (ILNM), as to date no validated prognostic tool is available for patients with pSCC and ILNM.

PATIENTS AND METHODS

The development cohort included 234 patients from seven referral centres. The external validation cohort included 273 patients from two additional referral centres. Cox regression identified predictors of any recurrence, which were used to develop a risk calculator. The risk-calculator grouped the development and the validation cohorts according to the individual risk of any recurrence at 24 months (24m-R). Adjuvant treatment effects were tested on overall survival (OS) according to the derived tertiles, within the development and validation cohorts.

RESULTS

Positive surgical margins, pN₃ , and ILNM ratio were associated with higher recurrence rate. The 2-year OS rates were lower for patients with high (>37%) and intermediate (19-37%) compared to low (<19%) 24m-R risk of recurrence, for both the development (43% and 58% vs 83%, P < 0.001) and validation cohort (44% and 50% vs 85%, P < 0.001). Results were confirmed in the subgroup of patients who did not receive adjuvant treatment (P < 0.001), but not in patients who did receive adjuvant treatments in both the development and validation cohorts (P > 0.1).

CONCLUSION

Adjuvant treatment planning is crucial in patients with pSCC with ILNM, where only weak evidence is available. The current tool proved to successfully stratify patients according to their individual risk, potentially allowing better tailoring of adjuvant treatments.

Nomogram prediction of overall survival based on log odds of positive lymph nodes for patients with penile squamous cell carcinoma

Purpose

This study aimed to establish a nomogram to predict the long‐term overall survival (OS) for patients with penile squamous cell carcinoma (PSCC).

Method

The PSCC patients receiving regional lymph node dissection (RLND) were enrolled from the Surveillance, Epidemiology, and End Results (SEER) database between 2004 and 2015. The dataset of all eligible patients were used to develop the predictive model. The significant independent predictors were identified through Cox regression modeling based on the Bayesian information criterion and then incorporated into a nomogram to predicted 1‐, 3‐, and 5‐year OS. Internal validation was performed using the bootstrap resampling method. The model performance was evaluated using Harrell's concordance index (C‐index), calibration plots, integrated discrimination improvement (IDI), net reclassification improvement (NRI), and decision curve analysis (DCA).

Results

Totally, 384 eligible PSCC patients were enrolled from the SEER database. A nomogram for OS prediction was developed, in which three clinical variables significantly associated with OS were integrated, including age, N classification, and log odds of positive lymph nodes (LODDS). The C‐index of the nomogram (0.746, 95% CI: 0.702‐0.790) was significantly higher than that of the American Joint Committee on Cancer (AJCC) staging system (0.692, 95% CI: 0.646‐0.738, P = .020). The bootstrap optimism‐corrected C‐index for the nomogram was 0.739 (95% CI: 0.690‐0.784). The bias‐corrected calibration plots showed the predicted risks were in good accordance with the actual risks. The results of NRI, IDI, and DCA exhibited superior predictive capability and higher clinical use of the nomogram compared with the AJCC staging system.

Conclusion

We successfully constructed a simple and reliable nomogram for OS prediction among PSCC patients receiving RLND, which would be beneficial to clinical trial design, patient counseling, and therapeutic modality selection.

Factors affecting lymph node sampling patterns and the impact on survival of lymph node density in patients with Wilms tumor: a Surveillance, Epidemiology, and End Result (SEER) database review

BACKGROUND

Lymph node (LN) involvement is an important prognostic indicator for patients with Wilms tumor (WT), and there have been previous reports of utilizing LN density (LND = positive LN/LNs examined) as an advanced metric to risk-stratify patients with WT.

OBJECTIVE

The purpose of this study was to describe patient characteristics that affect LN yield and assess the effect of LND on the overall survival (OS) in patients with WT, with the expectation that patients with LNDs above a critical cut-point would demonstrate lower OS.

STUDY DESIGN

The Surveillance, Epidemiology, and End Result (SEER) database was queried for all patients diagnosed with unilateral WT from 2004 to 2015. Patient and disease characteristics were collected, and Poisson regression was used to identify characteristics correlated with LN yield. LND was calculated for LN-positive patients, and multivariable survival analysis was performed, including patient demographics and LND as variables.

RESULTS

1489 patients with unilateral WT were identified for analysis, 231 (15.51%) of whom were LN-positive. Median patient age at diagnosis was three years (IQR 1-5). On Poisson regression, the year of diagnosis, patient age, tumor size and laterality, and stage were found to impact LN yield. For patients with positive LNs, five-year OS of patients with LNDs above 0.4 was worse than those below 0.4 (76.1% vs 89.6%, p = 0.041). On multivariable analysis, tumor size and LND remained significant predictors of OS.

DISCUSSION

Administrative databases such as SEER provide an excellent resource for studying conditions where large patient numbers for analysis are difficult to obtain. Unfortunately, the SEER database is unable to account for every factor that could affect LN sampling patterns. Additionally, favorable vs unfavorable histology is not available in SEER, and SEER utilizes its own staging system, which makes comparison to Children's Oncology Group staging difficult. Despite these limitations, the findings of this study are similar to those previously published using administrative databases analyzing LN sampling patterns and the effect of LND on OS in WT.

CONCLUSIONS

Analysis of the SEER database confirms that there are several patient- and disease-specific factors that affect the number of LNs sampled during nephrectomy for WT, and that LND may be a predictor of OS. These findings highlight the need for standardization of LN sampling patterns for pediatric renal tumors and support the investigation of LND in future studies to further risk-stratify WT patients to tailor therapy intensity.

Identifying an optimal lymph node yield for penile squamous cell carcinoma: prognostic impact of surgical dissection

OBJECTIVE

To evaluate the prognostic impact of lymph node yield (LNY) on survival outcomes for penile squamous cell carcinoma (SCC).

PATIENTS AND METHODS

In all, 532 patients who underwent inguinal LN dissection (ILND) across tertiary referral centres from Europe, China, Brazil and North America were retrospectively evaluated. From this cohort, 198 patients received pelvic LND (PLND).We identified threshold values for ILND and PLND using receiver operating characteristic curves. We tested prognostic value of LNY for recurrence-free survival (RFS), disease-specific survival (DSS), and overall survival (OS) using the Kaplan-Meir method and Cox proportional hazard regression models.

RESULTS

The median (interquartile [IQR]) age was 59 (49-68) years and the median (IQR) follow-up after ILND was 28 (12-68.2) months. Overall, 85% of the patients had bilateral dissections. The median (IQR) number of inguinal LNs removed was 15 (10-22). Of those receiving PLND, The median (IQR) number of LNs was 13 (8-19). A LNY of ≥15 was used for dichotomisation of ILND patients, and a LNY of ≥9 was used in the PLND cohort. Patients with a LNY ≥15 had significantly better 5-year OS vs patients with a LNY <15 (70.1% vs 58.7%). On multivariable analyses, a LNY ≥15 was a predictor of OS (hazard ratio [HR] 0.68, P = 0.029). For cN0 patients, a LNY ≥15 was an independent predictor of RFS (HR 0.52, P = 0.043) and OS (HR 0.53, P = 0.021). In the PLND cohort, a LNY ≥9 was a predictor of RFS (HR 0.53, P = 0.032).

CONCLUSIONS

Using one of the largest LND datasets to date, we found LNY to be a significant predictor of outcomes after lymphatic staging for penile SCC. Prospective validation is warranted.

Nomogram-based prediction of overall survival after regional lymph node dissection and the role of perioperative chemotherapy in penile squamous cell carcinoma: A retrospective multicenter study

OBJECTIVES

To improve the prognostic allocation of patients with penile squamous-cell carcinoma (PSCC) receiving regional lymph node dissection (LND).

PATIENTS AND METHODS

An international, multicenter, retrospective study was performed on patients with PSCC who received regional LND, with or without perioperative therapy, from 1980 to 2017. We first used a random forest (RF) method with missing data imputation. Additionally, data were modeled using Cox proportional hazard regression, and a Cox model was also fit including prespecified variables. Based on the latter model, a nomogram for estimating 12-month and 24-month overall survival (OS) was developed.

RESULTS

There were 743 patients who received LND at 7 referral centers from Europe, the USA, Brazil, and China. Of these patients, 689 were analyzed: 86 (12.5%) received neoadjuvant chemotherapy (NAC); 171 (24.8%) received adjuvant chemotherapy (AC), and 74 (10.7%) received adjuvant radiotherapy. The variables significantly associated with OS were age (P < 0.001), the pathologically involved/total removed LN ratio (P < 0.001), pN stage (overall P < 0.001), and NAC (P = 0.013). NAC and AC were ineffective in N1-2 patients (clinical and pathological, respectively), whereas they provided OS improvements in N3 patients. Finally, we developed a nomogram predicting 12- and 24-month OS based on prespecified variables (c-index: 0.75). The study is limited by its retrospective nature.

CONCLUSIONS

We propose a tool that can be offered as an aid to physicians to enhance decision-making, clinical research, and patient counseling whenever LND is needed for PSCC. Administration of NAC and AC should be restricted to clinical and pathological N3 patients, respectively.

Lymph node density predicts recurrence and death after inguinal lymph node dissection for penile cancer

Purpose

To determine the impact of lymph node density (LND) on survival after inguinal lymph node dissection (ILND) for penile cancer.

Materials and Methods

Our institutional penile cancer database was queried for patients who underwent ILND. Clinicopathologic characteristics including LND and total number of positive lymph nodes (LNs) were analyzed to determine impact on recurrence-free survival (RFS) and overall survival (OS). LND, or the percent of positive LN out of total LN, was calculated as a categorical variable at varying thresholds.

Results

Twenty-eight patients with complete follow-up were identified. Indications for ILND were stage >T2 in 20 patients (71.4%), palpable adenopathy in 7 (25%), high grade T1 in 1 (3.6%). Median node yield was 17.5 (interquartile range, 12−22), and positive LNs were found in 14 patients (50%). RFS and OS were significantly lower for patients with >15% LN density (median RFS: 62 months vs. 6.3 months, p=0.0120; median OS: 73.6 months vs. 6.3 months, p<0.001). Controlling for age, medical comorbidities, number of positive LN, T stage, pelvic LN status and indication, LN density >15% was independently associated with worse RFS (hazard ratio [HR], 3.6; p=0.04) and OS (HR, 73.6; p=0.002). The c-index for LND was higher than total positive LNs for RFS (0.64 vs. 0.54) and OS (0.79 vs. 0.61).

Conclusions

In this small, retrospective penile cancer cohort, the presence of nodal involvement >15% was associated with decreased RFS and OS, and outperformed total number of positive LN as a prognostic indicator.