Introduction

There is limited data to define an appropriate threshold for lymph node yield (LNY) following regional lymphadenectomy (rND) for penile squamous cell carcinoma (pSCC) and, whether that specific threshold impacts overall survival (OS). We sought to determine whether a specific LNY affects OS following rND for pSCC and, to define the minimum beneficial number of lymph nodes (LN) to retrieve.

Methods

Using the National Cancer Database (NCDB), we identified men diagnosed with pSCC, who underwent rND, from 2004 to 2013. We excluded men diagnosed on autopsy or at the time of death, with preoperative chemotherapy or radiotherapy, M+ disease, and with < 3 months of follow up. We assessed the statistical distribution of LNY following rND. A multivariable logistic regression model was developed to assess predictors of OS including: age, comorbidity, race, stage, grade, nodal status, and LNY. Kaplan-Meier (KM) survival analysis was performed to compare OS by varying thresholds of LNY.

Results

938 men with pSCC underwent rND. Of these 452 met inclusion criteria. Median follow up was 29.9 months. The median number of regional LN retrieved was 16. Based on the statistical distribution of LNY and, sensitivity analysis, a threshold of 15 LNs appeared to be clinically and statistically relevant. There was no significant difference in race, stage, grade for men with LNY ≤15 vs >15. However, men with LNY ≤ 15 were older than those with LNY >15 (64 vs 58 years, p<0.01). On multivariable analysis, significant independent predictors of worse OS were: age (HR: 1.02; CI [1-1.03], p<0.05), N+ disease (HR: 3.06; CI [2.12-4.42], p<0.001), and LNY ≤ 15 (HR: 1.62; CI [1.17-2.24], p<0.01). Men with a LNY ≤ 15 demonstrated a significantly decreased 5-year OS compared to those with LNY > 15 (50% VS 73%, p<0.05). On subgroup analysis of men with T2, N0, LNY >15 trended toward better 5-year OS vs LNY ≤15 (90% VS 71%, p=0.06) (Figure)

Conclusions

LNY following rND for pSCC appears to have an impact on OS independent of age, stage, nodal status and grade. A minimum LNY >15 following rND may have a beneficial impact on OS and may serve as the quantitative threshold for defining an adequate rND.

Funding

None