517 Dynamic sentinel lymph node biopsy in patients with invasive squamous cell carcinoma of the penis: A prospective study of the outcome of 500 inguinal basins assessed in a single institution

Background: Dynamic sentinel node biopsy (DSNB) in combination with ultrasound scan (USS) has been the technique of choice at our centre since 2004 for the assessment of nonpalpable inguinal lymph nodes (cN0) in patients with squamous cell carcinoma of the penis (SCCp). Sensitivity and false-negative rates may vary depending on whether results are reported per patient or per node basin, and with or without USS. Objective: To determine the long-term outcome of patients undergoing DSNB and USSguided fine-needle aspiration cytology (FNAC) in our cohort of newly diagnosed cN0 SCCp patients, as well as to analyse any variation in sensitivity of the procedure. Design, setting, and participants: A series of consecutive patients with newly diagnosed SCCp, over a 6-yr period (2004–2010), were analysed prospectively with a minimum follow-up period of 21 mo. All patients had definitive histology of T1G2 and nonpalpable nodes in one or both inguinal basins. Patients with persistent or untreated local disease were excluded from the study. Intervention: All eligible patients had DSNB and USS with or without FNAC of cN0 groins. Outcome measurements and statistical analysis: The primary end point was no nodal disease recurrence on follow-up. The secondary end point was complications after DSNB. Sensitivity of the procedure was calculated per node basin, per patient, with DSNB alone, and with USS with DSNB combined. Results and limitations: Five hundred inguinal basins in 264 patients underwent USS with or without FNAC and DSNB. Seventy-three positive inguinal basins (14.6%) in 59 patients (22.3%) were identified. Four inguinal basins in four patients were confirmed false negative at 5, 8, 12, and 18 mo. Two inguinal basins had positive USS and FNAC and negative DSNB results. Sensitivity of DSNB with USS, with and without FNAC, per inguinal basin was 95% and per patient was 94%. Sensitivity of DSNB alone per inguinal basin and per patient was 92% and 91%, respectively. The DSNB morbidity rate was 7.6%. Conclusions: DSNB in combination with USS has excellent performance characteristics to stage patients with cN0 SCCp, with a 5% false-negative rate per node basin and a 6% false-negative rate per patient.