Clinical Outcomes in Clinical N0 (cN0) Squamous Cell Carcinoma (SCC) of the Penis according to Nodal Management: Early, Delayed or Selective (following Dynamic Sentinel Node Biopsy - DSNB) Inguinal Lymph-Node Dissection (ILND)

Purpose: We evaluated the oncologic efficacy of early inguinal lymph-node dissection, observation or dynamic sentinel node biopsy followed by delayed or selective inguinal lymph-node dissection in cN0 patients with penile squamous cell carcinoma. Materials and methods: Between 1980 and 2017 (inclusive), 296 evaluable consecutive cN0 penile squamous cell carcinoma patients underwent early inguinal lymph-node dissection (16), observation (114) or dynamic sentinel node biopsy (166). Median followup was 50 months. Tumor stage, grade, lympho-vascular invasion and age were considered. Kaplan-Meier plots illustrated 5-year inguinal relapse-free and cancer specific survival rates. Multivariable Cox regression models tested the treatment effect. Analyses were repeated after inverse probability of treatment weighting adjustment. Results: The 5-year inguinal relapse-free survival and cancer specific survival rates following early, observation and dynamic sentinel node biopsy inguinal lymph-node dissection were 100%, 87%, 89%, and 84%, 81%, 85%, respectively. The 5-year crude inguinal relapse-free survival and cancer specific survival rates were 90% and 93% in low-risk patients undergoing observation. Clavien grade 3 complications were 0.6 vs 12.5% in the dynamic sentinel node biopsy and early inguinal lymph-node dissection group, respectively. After inverse probability after treatment weighting adjustment, 5-year inguinal relapse and cancer specific survival were 90% vs 73% and 90% vs 77% following dynamic sentinel node biopsy and observation, respectively. At multivariable Cox regression model, patients undergoing dynamic sentinel node biopsy had significantly lower inguinal relapse (HR 0.4, CI 0.2-0.85, p 0.02) and cancer specific mortality (HR 0.29, CI 0.11-0.77; p=0.01) compared to those under observation. The low number of patients undergoing early inguinal lymph-node dissection made a reliable comparison with this group impractical. Conclusions: Selective inguinal lymph-node dissection following dynamic sentinel node biopsy significantly improved inguinal relapse and cancer specific mortality when compared with observation, providing evidence of efficacy of dynamic sentinel node biopsy in clinical stage N0 squamous cell carcinoma of the penis.