Revisiting the “10% rule” in breast cancer sentinel lymph node biopsy: an approach to minimize the number of sentinel lymph nodes removed

Abstract Background Sentinel lymph node (SLN) biopsy (SLNB) is an accurate and proven axillary staging procedure for early breast cancer. The aim of this study was to determine if the “10% rule” is applicable to the performance of SLNB at the investigators' institution and if the criteria used for SLNB at their institution could be refined to minimize the number of SLNs removed. Methods Retrospective analysis was conducted of a prospectively collected breast cancer SLNB database. Standard statistical methods were used for data analysis. Results Five hundred nine patients underwent a SLNB for breast cancer over a 5 year period. A mean of 2.5 SLNs were removed per patient. All patients with SLN metastasis were identified within the 1st 4 SLNs removed. Conclusions The “10% rule” is best used as a guide at the investigators' institution. Strict adherence to this rule appears to result in the removal of an excessive number of lymph nodes, which may contribute to excessive health care costs and patient morbidity.