LAUSR

Sentinel lymph node biopsy (SLNB) is the mainstay of axillary staging for patients with clinically node-negative, early stage invasive carcinoma of the breast. However, patients with microinvasive disease (DCISM) present with a lower overall risk of nodal metastasis, reducing the potential value of axillary surgery in the majority of these cases. Our current study evaluated the rate of axillary lymph node involvement in DCISM using the National Cancer Database. Our findings demonstrated that the overall rate of sentinel node metastasis was 2.9%. Furthermore, the majority of lymph node involvement was limited to micrometastasis and isolated tumor cells (ITCs). The low rate of node involvement suggests that most patients with DCISM are exposed to the potential risks of axillary surgery without any clinical benefit. We continue to recommend SLNB for patients undergoing mastectomy and acknowledge the standard practice of SLNB in breast conservation (i.e., lumpectomy). In certain cases, SLNB results may affect adjuvant treatment decisions and should continue to be performed for this purpose. However, our study’s findings should factor in clinical decision-making for patients with DCISM, especially when considering returning to the operating room for SLNB in cases where an initial diagnosis of pure DCIS upstages to DCISM on final pathology. There may also be a role for special consideration if there are concerns about morbidity from additional axillary surgery. Ideally, advances in preoperative clinical assessment would provide new methods for determining the risk of disease in axillary nodes, allowing surgeons to omit SLNB on a routine basis safely. With the vast majority of patients being pathologically node-negative, developing a better selection process for SLNB would reduce the burden of unnecessary surgery while identifying the few patients with DCISM who truly warrant axillary surgery.