Can sentinel node biopsy after neoadjuvant systemic chemotherapy (NAC) be safely omitted in selected patient with early breast cancer?

Abstract

564 Background: There is a recent trend of performing minimum axillary surgery considering the prognostic value and fewer complications for primary breast cancer patients since the results of ACOSOG Z011. Nodal status after NAC is not be useful for postoperative treatment in most of cN0 patients. Therefore, sentinel node biopsy (SNB) may be omitted if ypN0 after NAC can be predicted in cN0 patients. We assessed clinicopathological factors associated with ypN0 after NAC in cN0 primary breast cancer patients. Methods: Two-institutional retrospective cohort study of clinically N0 breast cancer patients before NAC and who underwent breast surgery was conducted, including 419 consecutive patients between 2009 and 2016 in St. Luke's International Hospital and St. Marianna University School of Medicine hospital. Each institutional review board approved this study. In the patients with or without nodal metastasis on SNB after NAC, we compared clinicopathological factors including Estrogen Receptor (ER), Progesterone Receptor (PgR), human epidermal growth factor receptor 2 (HER2), Ki-67 on needle biopsy specimens, and tumor size before and after NAC on MRI findings. Results: Of the 419 patients, 380 patients (90.7%) were ypN0 and 39 patients (9.3%) were ypN+ after NAC. In univariate analysis, clinical complete response of primary tumor on MRI findings (MRI-CR) (p<0.01), ER-negative (p<0.01), PgR-negative (p<0.01), and high-Ki-67 >30% (p<0.01) were significantly associated with ypN0 on SNB after NAC. In multivariate analysis, MRI-CR (HR 5.12, p<0.01) and high-Ki-67 (HR 2.86, p<0.01) were independent predictive factors of ypN0 after NAC.According to breast cancer subtype, only one of 72 ER-negative and HER2-positive had significantly low risk of ypN+ (1.3%) comparing other subtypes (p<0.01). Conclusions: Achieving cCR of primary tumor after NAC and high-Ki67 in cN0 patients, especially in HER2 type breast cancer, might have ypN0. We are conducting prospective study to omit SNB for these populations based on these results,