Inguinal lymph nodal metastasis is the most important prognostic factor in Penile squamous cell carcinoma (PSCC). Lymph node density (LND), is defined as the total number of positive lymph nodes (LNs) divided by the total number of LNs removed, expressed as a percentage. LND in penile cancer has been studied previously in other studies with a cut-off of 6.7% to 16% being suggested as a clinically significant prognostic parameter, which correlates with disease outcomes.

A retrospective analysis of 105 cases diagnosed as PSCC who had undergone primary surgical treatment with/without either upfront or follow-up unilateral/bilateral inguinal node dissection was performed. Disease-free survival (DFS) was calculated by Kaplan Meier analysis. A cutoff for LND was defined by plotting a receiver operating characteristic curve and using the highest Youden's index as a discriminator.

After excluding cases where nodal dissection was negative, we had a total of 40 cases for analysis of LND. The median of positive LNs was 2 (1-15) and total LNs dissected was 19 (12-45). Median DFS was 9 months in those with positive LNs (n=40). Median LND was 10.43% (3.45-75%). A cut-off of 28.8% with a Youden's index of 0.4 on the other hand was found clinically significant cut- off for LND for this cohort

LND is an under-recognized parameter with few studies validating its prognostic impact in PSCC. Our study did not show a statistical difference between the two groups using a cutoff of 6.7%. Although the cutoff of 28.8% did show a difference in DFS for the two groups, there was an unequal distribution of cases in both groups. Nonetheless, a higher cut-off should be explored in future studies, particularly in our region where patients frequently present with advanced stages and matted LNs. Reference:1. Svatek RS, Munsell M, Pettaway CA et al. J Urol. 2009;182(6):2721-7.