Nomogram-based prediction of overall survival after regional lymph node dissection and the role of perioperative chemotherapy in penile squamous cell carcinoma: A retrospective multicenter study

Objectives: To improve the prognostic allocation of patients with penile squamous-cell carcinoma (PSCC) receiving regional lymph node dissection (LND). Patients and methods: An international, multicenter, retrospective study was performed on patients with PSCC who received regional LND, with or without perioperative therapy, from 1980 to 2017. We first used a random forest (RF) method with missing data imputation. Additionally, data were modeled using Cox proportional hazard regression, and a Cox model was also fit including prespecified variables. Based on the latter model, a nomogram for estimating 12-month and 24-month overall survival (OS) was developed. Results: There were 743 patients who received LND at 7 referral centers from Europe, the USA, Brazil, and China. Of these patients, 689 were analyzed: 86 (12.5%) received neoadjuvant chemotherapy (NAC); 171 (24.8%) received adjuvant chemotherapy (AC), and 74 (10.7%) received adjuvant radiotherapy. The variables significantly associated with OS were age (P < 0.001), the pathologically involved/total removed LN ratio (P < 0.001), pN stage (overall P < 0.001), and NAC (P = 0.013). NAC and AC were ineffective in N1-2 patients (clinical and pathological, respectively), whereas they provided OS improvements in N3 patients. Finally, we developed a nomogram predicting 12- and 24-month OS based on prespecified variables (c-index: 0.75). The study is limited by its retrospective nature. Conclusions: We propose a tool that can be offered as an aid to physicians to enhance decision-making, clinical research, and patient counseling whenever LND is needed for PSCC. Administration of NAC and AC should be restricted to clinical and pathological N3 patients, respectively.