Microinvasive breast cancer and the role of sentinel node biopsy: an institutional experience and review of the literature.

Ductal carcinoma in situ with microinvasion (DCISM) is a distinct clinicopathologic entity. Its true metastatic potential has been unclear, due in part to historical differences in the definition of microinvasion. The role of routine axillary staging for DCISM is controversial, given the reportedly low incidence of axillary metastases. We describe our institutional experience with DCISM, and define the role of axillary staging. A retrospective analysis was made of patients with DCISM. Forty-four patients underwent axillary staging (24 axillary lymph node dissection [ALND], 22 sentinel node biopsy [SNB]). Macrometastatic disease was present in three patients (7%), and two patients had isolated tumor cells (itc) in the sentinel node. Patients with axillary metastases tended to be younger. Comedonecrosis, nuclear grade, multifocal microinvasion or presentation as a clinical mass was not associated with a higher rate of axillary metastases. In this series, 7% of patients had macrometastatic disease, and two patients (5%) had itc only. Axillary staging is indicated, and SNB is appropriate for the identification of axillary metastatic disease.