AB195. 194. Clinicopathological features and management of metaplastic breast cancer: a single institution experience

Background: Metaplastic breast carcinoma (MBC) is a rare heterogenous histopathological subtype of primary breast carcinoma arising from both epithelial and mesenchymal elements. It accounts for <1% of all breast malignancies. MBC has poor outcomes relative to invasive ductal carcinoma and the optimal treatment approach remains largely unknown. We aimed to examine the clinicopathological features and management of patients diagnosed with MBC in our institution over a 10-year period.

Methods: All patients diagnosed with MBC between 2007 and 2017 were identified from the histopathology database. Data regarding patient demographics, mode of presentation, tumour characteristics, treatment modalities and presence of recurrence or metastatic disease were reviewed and analysed.

Results: There were 21 patients diagnosed with MBC; 14 (67%) patients presented clinically while 7 (33%) were detected radiologically. The two most common histological subtypes were squamous (19%) and chondroid differentiation (19%). Most tumours were grade 3 (67%) and almost exclusively triple-negative (95%). Only 4 (19%) patients had nodal involvement. Fifteen (71%) patients had primary surgery while 4 (19%) had neoadjuvant chemotherapy with further surgery. In terms of adjuvant treatment, 6 (28%) patients received chemotherapy and 14 (67%) had radiotherapy. Four (19%) patients developed metastatic disease within 5 years of diagnosis.

Conclusions: Our institutional experience in treating MBC demonstrates that these tumours are high grade with an associated high relapse rate. Further studies on the molecular characteristics of MBC may help us to identify effective therapies in the treatment of these patients.

Keywords: Metaplastic; breast carcinoma; management; institutional; experience