Background: The aim of this study was to validate lymphovascular invasion (LVI) as a predictor of lymph-node invasion (LNI) in squamous cell carcinoma of the penis (SCCP).
Methods: Within the Surveillance, Epidemiology, and End Results database (2010-2020), we identified SCCP patients who underwent lymphadenectomy with known LVI status. Univariable logistic regression models (LRMs) addressed LNI. Harrell's concordance index (c-index) quantified accuracy after 2000 bootstrap resamples for internal validation. Multivariable LRMs included the most informative, statistically significant predictors. Subgroup analyses were repeated in organ-confined (T1b-T2) and non-organ confined (T3-T4) stages.
Results: Of 586 SCCP patients, 219 (37%) had LVI. LVI was associated with higher rate of LNI (66 vs. 43%; P<0.001). Positive predictive value of LVI was 66 vs. 57% for negative predictive value. In multivariable LRMs, LVI independently predicted LNI (Odds ratio [OR]: 2.41; P<0.001). Bootstrap-adjusted c-index of multivariable model was 0.570 without LVI vs. 0.639 with LVI. In subgroup analyses, LVI independently predicted LNI in organ-confined (OR: 2.23; P<0.001) and in non-organ confined stages (OR: 3.10; P<0.001). In subgroup analyses, addition of LVI increased c-index from 0.530 to 0.595 in organ-confined and from 0.599 to 0.682 in non-organ confined.
Conclusions: The current study validates LVI as an independent predictor of LNI in SCCP. LVI increases the accuracy of LNI predictions in the overall cohort as well as in organ-confined and non-organ confined stages. However, stage and grade even with the added consideration of LVI are not accurate enough to provide LNI prediction in individual patients.