Sentinel Node Identification with Hybrid Tracer-guided and Conventional Dynamic Sentinel Node Biopsy in Penile Cancer: A Prospective Study in 130 Patients from the Two National Referral Centres in Sweden
Christian Torbrand, Åsa Warnolf, Dominik Glombik, Sabina Davidsson, Jessica Carlsson, Gediminas Baseckas, Ulf Håkansson, Elin Trägårdh, Håkan Geijer, Fredrik Liedberg, Peter Kirrander
Abstract
BACKGROUND: Tc-nanocolloid tracer improves sentinel node (SN) identification compared to conventional dynamic sentinel node biopsy (DSNB). OBJECTIVE: To investigate hybrid tracer-guided SN identification in a multicentre setting and determine false-negative (FN) and complication rates. DESIGN, SETTING, AND PARTICIPANTS: Tc-nanocolloid hybrid tracer was used in the standard DSNB protocol. INTERVENTION: SNs were identified intraoperatively using radioguidance, fluorescence imaging, and blue dye. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: and McNemar's tests. RESULTS AND LIMITATIONS: Overall, 453 SNs were identified preoperatively via single-photon emission computed tomography/computed tomography. Among the 425 SNs excised, radioguidance, fluorescence, and blue dye identified 414 (97%), 363 (85%), and 349 (82%), respectively. Fluorescence imaging helped to detect six SNs that were negative using the other tracers, two of which were from the same patient and contained metastases. Histopathological examination detected 33 metastatic SNs in 20/130 patients (15%). The FN rate was 12% per groin (95% confidence interval 8-16%). CONCLUSIONS: Identification of SNs in patients with penile cancer relies mainly on radioguidance, while fluorescence (ICG) and blue dye methods for optical SN identification are comparable. However, the value of fluorescence imaging should be further evaluated in studies with long-term follow-up. PATIENT SUMMARY: In this study, we investigated addition of a dye called indocyanine green (ICG) for assessment of lymph nodes in patients with cancer of the penis. ICG did not improve the rate of detection of nodes most likely to harbour cancer because of their location in the drainage pathway for lymphatic fluid, but did help in identifying additional metastases.