Abstract P1-01-22: The utility of axillary ultrasound and sentinel lymph node biopsy in the management of metaplastic breast carcinoma

Abstract

Abstract Background: Metaplastic breast carcinoma (MBC) accounts for <5% of all breast malignancies. This entity represents a heterogenous group of tumors in which the adenocarcinomatous element is admixed with one or more neoplastic mesenchymal (spindle, squamous, chondroid, or osseous) elements. Patients typically present with large triple negative tumors and have a poor prognosis. The likelihood of lymph node (LN) involvement has been reported to be low in MBC patients. Due to the paucity of data, we undertook this study to explore the role of axillary ultrasound (US) and sentinel LN biopsy (SLNB) in the management of MBC. Methods: With IRB approval, we retrospectively identified patients diagnosed with MBC from 2001–2011 from the surgical pathology database. Histopathology and imaging were reviewed. Demographic, treatment and outcome data were obtained by clinical chart review. Data were analyzed using JMP 9.0 software. Results: We identified 41 women with MBC. Median age was 60 years (range 33–90). Histologic subtypes were spindle cell (46%), mixed adenocarcinoma and mesenchymal elements (20%), squamous cell (17%) chondroid/osseous (10%) and adenosquamous (7%). Tumor stage was T1 (24%), T2 (44%), T3 (12%) and T4 (20%). 26 patients (63%) were treated by mastectomy and 15 (37%) by wide excision. Of the 38 patients who underwent LN surgery (6 low-grade MBC, 32 intermediate/high-grade MBC), 10 (26%) were LN positive. All low-grade MBC patients were LN negative while 10 of 32 intermediate/high-grade MBC patients (31%) had LN metastasis. 22 patients had a preoperative axillary US. 14 patients had a negative axillary US and none had LN metastasis. 4 of 8 patients with suspicious axillary US findings had a preoperative axillary LN fine needle aspiration biopsy (FNAB) and 3 were positive for cancer. These patients proceeded directly to axillary LN dissection (ALND). 24 patients had a SLNB of whom one was SLN positive and underwent completion ALND. LN metastasis was associated with larger tumor size (p = 0.003), higher tumor grade (p = 0.04), angioinvasion (p = 0.07) and abnormal axillary US (p = 0.003). Surviving patients were followed for a mean (median) of 41 (30) months during which 13 (32%) recurred at a median of 6 months (IQR 3–17 months) and 11 (27%) subsequently died of disease. One SLN negative patient developed an axillary recurrence at 8 months, was successfully treated by ALND and is disease-free at 38 months. There were no axillary LN relapses after ALND. Conclusions: For clinically node-negative MBC patients, our contemporary data series suggests the incidence of occult LN metastasis is sufficiently high to warrant LN staging especially for patients with intermediate and high-grade tumors. This can be accomplished in a minimally invasive fashion with reasonable accuracy (∼97%) with axillary US, FNAB of sonographically suspicious LNs, and SLNB for patients with negative axillary US or FNAB. Axillary LND should be performed for patients with clinically and/or FNAB-positive LN for enhanced disease control. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-01-22.