Inguinal Lymph-Node Ratio (LNR) as a predictor of Pelvic Lymph-Node Metastasis in squamous cell carcinoma of penis

Objective: To determine the predictors of pelvic lymph-node metastasis in cases of squamous cell carcinoma (SCC) of penis.

Methods: Data was retrospectively collected from 267 cases of SCC penis that presented at our institute between 2009 and 2019. Univariate and multivariate logistic regression models were used to identify independent significant factors. Receiver Operating Characteristic (ROC) curve was used to determine the cut-off of Lymph-Node Ratio (LNR) and discriminative ability of new model. Survival analysis was done using Kaplan Meier Curve.

Results: Pelvic Lymph-Node Metastasis (PLNM) was pathologically detected in 56 groins (29.2%). A cut-off of 0.25 was calculated for LNR based on ROC. LNR >0.25 (p = 0.003), ENE (p = 0.037), and LVI (p = 0.043) were found significant on multivariate logistic regression. 71.5% showed PLNM in groins with positive LN (PLN) </ = 2 but LNR >0.25 whereas no PLNM was seen in groins with PLN >2 but LNR </ = 0.25. The AUC was 0.918 and 0.821 for LNR and PLN respectively. The probability of finding PLNM was 0% for patients with no risk factors which increased to 83% for 3 risk factors. The 5-year survival was 60% if no PLNM was found as compared to 12.7% if PLNM were found. The survival according to risk score was 81%, 43%, 16% and, 13% for 0, 1, 2 and, 3 risk score respectively.

Conclusion: LNR >0.25, LVI and, ENE are independent predictors of PLNM. The discriminative ability of LNR was better than PLN. PLND could be avoided if no risk factors are present.