Prognostic Factors for Occult Inguinal Lymph Node Involvement in Penile Carcinoma and Assessment of the High-Risk EAU Subgroup: A Two-Institution Analysis of 342 Clinically Node-Negative Patients

Background

The European Association of Urology (EAU) guidelines advise an elective bilateral lymphadenectomy in clinically node-negative (cN0) patients with high-risk penile carcinoma (≥pT2, G3, or lymphovascular invasion LVI]).

Objective

Our aim was to assess prognostic factors for occult metastasis and to determine whether current EAU guidelines accurately stratify patients at high risk.

Design, setting, and participants

Data of 342 cN0 patients with histologically proven invasive penile squamous cell carcinoma who had undergone the current dynamic sentinel node biopsy (DSNB) protocol were analysed. A complete ipsilateral inguinal lymphadenectomy was only done if the sentinel node was tumour positive.

Measurements

The presence of occult metastasis was established by preoperative ultrasound and tumour-positive fine-needle aspiration cytology, tumour-positive sentinel nodes, and groin metastases during follow-up after a negative DSNB procedure. Median follow-up was 31 mo.

Results and limitations

Sixty-eight of 342 patients (20%) and 87 of 684 groins (13%) had occult nodal involvement including 6 patients (2%) with a groin metastasis after negative DSNB. Corpus spongiosum invasion, corpus cavernosum invasion, histologic grade, and LVI were each significant prognosticators for occult metastasis on univariate analysis. On multivariate analysis, grade (odds ratio OR]: 3.3 for intermediate and 4.9 for poor, respectively) and LVI (OR: 2.2) remained predictive factors. In total, 245 patients (72%) were classified high risk according to EAU guidelines. Among them, the incidence of occult metastasis was 23% (57 of 245). A potential limitation of this study is the lack of external review.

Conclusions

Histologic grade and LVI are independent prognostic factors for occult metastasis in penile carcinoma. Although both predictors are incorporated into the current EAU guidelines, the stratification of patients needing a lymph node dissection is inaccurate. Approximately 77% of high-risk patients (188 of 245) would have had a negative bilateral inguinal lymphadenectomy. For the time being, DSNB is considered a more suitable staging method than EAU risk stratification for an accurate determination of patients who require lymph node dissection.