Contemporary Incidence and Predictors of Occult Inguinal Lymph Node Metastases in Men With Clinically Node-negative (cN0) Penile Cancer

Abstract

To (1) examine the contemporary incidence of occult inguinal LN metastases and (2) identify predictors of occult inguinal LN metastases to improve selection of cN0 patients for inguinal lymphadenectomy (ILND). We identified 590 men with cTany cN0 cM0 penile cancer who underwent partial/radical penectomy and ILND from 2006-2016 in the NCDB. Rates of pN+ disease were examined, and a multivariable regression model was constructed to identify features associated with pN+ disease. Tumors were ≤pT1 in 21%, pT2 in 43%, and pT3/pT4 in 24% of patients. A median of 15 (IQR 8-22) LNs were removed at ILND. The overall pN+ rate was 24% and did not vary over the study period. The pN+ rate, stratified by pT stage, varied from 18-33%. On multivariable analysis, only higher tumor grade (OR 2.16; P=0.02 for grade 2; OR 2.81; P=0.005 for grade 3-4, versus grade 1) and lymphovascular invasion (OR 3.12; P <0.001) were independently associated with pN+ disease, whereas pT stage was not. The contemporary rate of occult LN metastases in men with cN0 penile cancer remains high at approximately 24%. Our results suggest that high tumor grade and/or lymphovascular invasion are better determinants of lymph node involvement than primary tumor stage.