Predictors of Pelvic Lymph Nodal Metastasis in Penile Squamous Cell Carcinoma- Results From a Matched-Pair Analysis

Introduction Pelvic lymph node (PLN) metastasis has a worse prognosis in penile squamous cell carcinoma. This study sought to determine the predictors of PLN metastasis in penile SCC. Materials and Methods This retrospective study included primary penile resections with inguinal lymph nodes (ILN) and PLN dissections over 10 years (2007-2017). A subset of treatment naïve cases with PLN metastasis was matched for age and tumor size with another subset of cases having metastatic ILN and negative PLN. The variables were correlated with the PLN metastasis using appropriate statistical tests. Internal validation of the multivariate model was conducted by using 2000 bootstraps on the same cohort. The optimum cut-off for the number of positive ILN was obtained by plotting a receiver operating characteristic curve and using the highest Youden’s index as a discriminator. Results A total of 56 cases (28 in each subset) formed the study cohort. On unadjusted analysis the size of the largest ILN (p=0.038), number of positive ILN (p=0.001), percentage of positive ILN (p=0.001), and laterality of ILN involvement (p=0.007) had a significant correlation with PLN metastasis. On adjusted analysis, the number of positive ILN (p=0.011) was the only statistically significant variable. Bootstrapping results indicated that this multivariate model represented the dataset adequately. The maximum Youden’s index was obtained when ≥5 ILN were positive. Conclusions The number of metastatic ILN is the most important predictor of PLN metastasis. A higher threshold of metastatic ILN for addressing PLN dissection can be investigated, particularly in a high disease burden setup.