Sentinel Node Mapping in Penile Cancer: An Update on Methods and Pitfalls

Penile cancer is a rare malignancy in which inguinal lymph node status is the main prognostic factor. Metastatic spread follows a predictable pattern, with nearly all cases initially involving the inguinal nodes. Among clinically node-negative (cN0) patients, up to 20%-25% may harbour occult inguinal metastases. The dynamic sentinel node biopsy (DSNB) technique has been developed over several decades as a minimally invasive method to accurately stage patients with cN0 penile cancer. As noninvasive imaging methods currently lack sufficient accuracy, DSNB remains the gold standard for nodal staging in these patients. This review outlines the DSNB technique, emphasizing its multidisciplinary nature and highlighting local variations in practice between centres, which may partly explain differences in the reported average false-negative rate of approximately 12%-13%. We also discuss management strategies for radio-tracer-silent groins and the intraoperative use of frozen section analysis of sentinel nodes, which may permit same-session radical inguinal lymph node dissection (ILND) when metastases are detected. Emerging innovations, including the use of magnetic nanoparticles as alternatives to radioactive tracers and advances in circulating tumour DNA (ctDNA) analysis, may further refine or eventually replace DSNB. Ongoing multidisciplinary efforts should aim to optimize all aspects of the technique to reduce false-negative rates and procedure-related morbidity. Fewer than 20% of patients with metastatic sentinel nodes have additional metastases after ILND. Refining DSNB to better identify patients who truly benefit from ILND would further be an important step, as current guidelines likely lead to overtreatment in more than 80% of these cases.