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.

4640 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 non palpable inguinal lymph nodes in patients with squamous cell carcinoma of the penis (SCCp). Sensitivity/false-negative rates may vary depending on whether results are reported per patient or per node basin and with and without USS. The purpose of this study was to determine the long-term outcome of DSNB and ultrasound-guided fine needle aspiration cytology (FNAC) in our cohort of newly diagnosed patients and to analyse any variation in sensitivity of the procedure. Methods: A prospective cohort study over 6 years (2004 to 2010). Inclusion criteria: New diagnosis SCCp, T1G2 or greater definitive histology, non-palpable nodes in inguinal basin. Exclusion: patient with persistent/untreated local disease. Sensitivity of the procedure was calculated, per node basin, per patient, DSNB alone, USS/DSNB combined. Minimum follow up 12 months. Results: 500 inguinal basins in 264 patients underwent USS+/-FNAC and DSNB. 70 (14%) positive inguinal basins in 57(22%) patients were identified. 9 (2%) inguinal basins had no tracer uptake. 2 inguinal basins were confirmed false negative at 8 and 12 months. 2 inguinal basins had positive USS+FNAC and negative DSNB. Overall sensitivity of the technique is reported in the table. Conclusions: DSNB in combination with USS has excellent performance characteristics to stage patients with clinically node-negative penile cancer with a 3% false negative rate. USS improves performance by 4% over DSNB alone. There is no difference in performance of the combined technique if it is reported per node basin or per patient. [Table: see text]