Validation of the prognostic value of lymph node ratio in patients with penile squamous cell carcinoma: a population-based study

A laparoscopic radical inguinal lymphadenectomy approach partly preserving great saphenous vein branches can benefit for patients with penile carcinoma

Background

Inguinal lymphadenectomy (iLAD) is effective for penile carcinoma treatment, but usually results in many complications. This study aims to clinically evaluate the feasibility and clinical significance of a laparoscopic radical iLAD approach partly preserving great saphenous vein branches for penile carcinoma patients.

Methods

A total of 48 patients with penile cancer who underwent laparoscopic radical iLAD with retention of the great saphenous vein in Henan Cancer Hospital from 2012 Jan to 2020 Dec were included in this study. Sixteen penile carcinoma patients who underwent laparoscopic radical iLAD preserving parts of superficial branches of the great saphenous vein were identified as the sparing group, and the matched 32 patients who incised those branches were identified as control group. This new procedure was performed by laparoscopy, preserving parts of superficial branches of the great saphenous vein, superficial lateral and medial femoral veins. Clinicopathological features and perioperative variables were recorded. Postoperative complications, including skin flap necrosis, lymphorrhagia, and lower extremity edema were analyzed retrospectively.

Results

We found that the operative time of the sparing group is significantly longer than the control group (p = 0.011). There was no statistical difference in intraoperative blood loss, the lymph node number per side, average time to remove the drainage tube and postoperative hospital stay between the two groups. Compared to the control group, the sparing group showed a significantly decreased incidence of lower extremity edema (p = 0.018). The preservation of parts of superficial branches of the great saphenous vein was mainly decreased the incidence of edema below ankle (p = 0.034).

Conclusions

This study demonstrated that the iLAD with preserving parts of superficial branches of the great saphenous vein, with a decreased incidence of postoperative complications, is a safe and feasible approach for penile cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12893-022-01582-3.

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.

The appropriate number of negative lymph nodes dissection for nonmetastatic penile cancer

Negative lymph nodes status has been attached more attention as a prognostic indicator for nonmetastatic penile cancer. We aimed to identify the appropriate number of negative lymph nodes dissection for nonmetastatic penile cancer using the Surveillance, Epidemiology and End Results database. A total of 1,470 nonmetastatic patients with penile squamous cell carcinoma were identified during 2004 and 2013. All patients were categorised according to different risk levels and lymphadenectomy. Univariate and multivariate Cox regression analyses were performed to evaluate the relationship between prognostic risk factors and cancer-specific survival. The optimal cut-off value of negative lymph nodes dissection was determined using the X-Tile program. A total of 1,470 patients were categorised into low- (pT1G1), intermediate- (pT1G2) or high-risk (pT1G3 and all higher stages) groups. In multivariate Cox analysis, lymphadenectomy improved the cancer-specific survival for patients in high-risk group (p = 0.014). Further, the optimal cut-off value of negative lymph nodes dissection for high-risk patients was 5 and patients with >5 negative lymph nodes had a higher cancer-specific survival (χ²  = 9.3676, p < 0.05). Therefore, lymphadenectomy improved survival for high-risk penile cancer and the removal of more than five negative lymph nodes was correlated with higher cancer-specific survival for high-risk patients who underwent lymphadenectomy.

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.

Development of a New Classification Method for Penile Squamous Cell Carcinoma Based on Lymph Node Density and Standard Pathological Risk Factors: The ND Staging System

Object: In this study, we evaluated the role of lymph node density (LND) and validated whether LND increases the accuracy of survival prediction when combined with the American Joint Committee on Cancer (AJCC) pathological node (N) staging system for penile cancer (7^th edition).

Methods: A total of 270 Chinese penile cancer patients treated between March 1999 and October 2014 were retrospectively analyzed. LND was analyzed as a trichotomous variable for the prediction of DSS in this cohort. We developed a new prediction model, which we refer to as the ND staging system, that is based on LND and pathological N staging. The predictive accuracy of this model was further assessed using the concordance index.

Results: LND was correlated with the laterality of lymph node metastasis, extranodal extension, pelvic lymph node metastases, and pathologic tumor (T) and N stages (P<0.05). In separate multivariate Cox regression models, the LND (hazard ratio [HR], 1.966, 95% confidence interval [CI], (1.112-3.473, P=0.020) yielded independent effects on the outcome. According to the LND classification, the 3-year disease-specific survival (DSS) rates for patients with LNDs <7.0%, 7.0 to 16.9%, and ≥17.0% were 90.9%, 66.5%, and 22.2%, respectively (P_{<7.0%; 7.0%-16.9%}=0.006; P_{7.0-16.9%; ≥17.0%}=0.001). The corresponding rates were 95.7%, 76.7%, and 28.1% for the ND1, ND2, and ND3 patients, respectively (P_ND1-ND2=0.047; P_ND2-ND3<0.001). The indexes indicated that the accuracy of the pathological ND category that incorporated LND was significantly increased.

Conclusion: LND was associated with some prognosticators and is thus a prognostic factor. The ND staging system that incorporates the LND better reflects the prognoses of penile cancer patients.

Modification of N staging systems for penile cancer: a more precise prediction of prognosis

BACKGROUND

The tumour-node-metastasis (TNM) classification is the most widely used tool for penile cancer. However, the current system is based on few studies and has been unchanged since 2009. We determined whether a modified pathological N staging system that incorporates the laterality and number of lymph node metastases (LNMs) increases the accuracy of the results in predicting survival compared with the 7th edition of the pathological N staging system of the American Joint Committee on Cancer (AJCC) for penile cancer.

METHODS

The clinical and histopathologic data from 111 patients with penile cancer with LNMs were analysed. Univariate and multivariate Cox proportional hazard regression analyses were used to determine the impact of the clinical and pathological factors on disease-specific survival of these patients. The predictive accuracy was further assessed using the concordance index.

RESULTS

According to the 7th edition of the pathological N classification, the 3-year disease-specific survival (DSS) rates for patients with pN1, pN2, and pN3 disease are 89.6%, 65.9%, and 33.6%, respectively (P(N1-N2)=0.030, P(N2-N3)<0.001, P<0.001). Under the modified pathological N category criteria, the 3-year DSS rates for pN1, pN2, and pN3 patients were 90.7%, 60.5%, and 31.4%, respectively (P(N1-N2)=0.005, P(N2-N3)=0.004, P<0.001). In separate multivariate Cox regression models, only modified N stages (hazard ratio: 4.877, 10.895; P=0.018, P<0.001) exhibited independent effects on the outcome. The accuracy of the modified pathological N category was significantly increased.

CONCLUSIONS

The modified pathological N staging system is a better reflection of the prognosis of patients with penile cancer. Our study should contribute to the improvement of prognostic stratification and systemic treatment to avoid overtreatment of patients.