Mp61-12 Does the “10% Rule” Apply to Sentinel Node Biopsies for Penile Squamous Cell Carcinoma?

You have accessJournal of UrologyPenile & Testicular Cancer II (MP61)1 May 2024MP61-12 DOES THE "10% RULE" APPLY TO SENTINEL NODE BIOPSIES FOR PENILE SQUAMOUS CELL CARCINOMA? Sylvia Yan, Benjamin Ayres, Holly Ni Raghallaigh, Rachel Oliver, and Nicholas Watkin Sylvia YanSylvia Yan , Benjamin AyresBenjamin Ayres , Holly Ni RaghallaighHolly Ni Raghallaigh , Rachel OliverRachel Oliver , and Nicholas WatkinNicholas Watkin View All Author Informationhttps://doi.org/10.1097/01.JU.0001009536.58867.87.12AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Inguinal dynamic sentinel biopsies (DSNB) is a minimally invasive way of staging squamous cell carcinoma of the penis (pSCC) for patients with clinically node negative (cN0) disease. The number of nodes removed positively correlates with increased morbidity as described in breast cancer and is clinically evident in our practice. The "10% rule" has been used in breast cancer whereby radioactive nodes are excised until a background count of <10% of total radioactivity is seen, and no further nodes are then removed. This assumes that low count nodes are not positive. Based on this, we conducted a study of DSNB, evaluating positivity and radioactive count. METHODS: A prospectively collected database of all patients treated at our tertiary referral centre was reviewed. All patients with cN0 pSCC who underwent DSNB staging between November 2020 and December 2022 were included. Our practice to date has been to remove all radioactive or blue nodes down to a background radioactivity count of <100MBq (1–3% of total nodal count). RESULTS: 298 inguinal basins were staged by DSNB within the 2-year period. Median follow up 15.5 months (IQR 9–22.3). 30 (10%) of the basins were positive for metastatic spread of SCC. 87% (n=26) of the 30 positive basins had a positive node that had a radioactive count of >20% of total activity. In 7% (n=2), the count of the positive node was between 10–20% of the total activity. In the remaining 2 cases, 1 groin had a positive node count between 1–10% of the total activity and the other had a positive node count of <1% of the total activity. This positive node was found to have a 7 mm metastatic deposit, not a fully involved node. Over the follow up period, no patients developed nodal recurrence. CONCLUSIONS: The results from our high-volume tertiary referral centre have indicated that in the majority (93%) of cases, applying the "10% rule" would accurately stage the inguinal basin. However, applying the 10% cut-off would have missed 7% of positive nodes. If the threshold were to be shifted to achieving a background radioactive count of 1%, the false negative rate would be 3%. Our data has shown that although the DSNB technique in penile cancer originated from experience in breast cancer, the "10% rule" may not necessarily translate and be applicable for our practice. Further research into identifying whether fewer lymph nodes can be safely excised during DSNBs is important to try and reduce morbidity of this staging procedure. Source of Funding: N/A © 2024 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 211Issue 5SMay 2024Page: e1016 Advertisement Copyright & Permissions© 2024 by American Urological Association Education and Research, Inc.Metrics Author Information Sylvia Yan More articles by this author Benjamin Ayres More articles by this author Holly Ni Raghallaigh More articles by this author Rachel Oliver More articles by this author Nicholas Watkin More articles by this author Expand All Advertisement PDF downloadLoading ...