Nelson Yit Ling Fung, Tan Puay Hoon, Benita Tan, Sim Yirong and Wong Fuh Yong
Retrospective study on outcomes in metaplastic breast cancer
Abstract Disclosures

Abstract
Background: Metaplastic breast cancer is recognised as a unique histologic subtype that accounts for less than 1% of breast cancers. However, it is an important histology to ascertain as previous studies have shown a greater tendency for higher grade metaplastic breast cancers to be aggressive locally, associated with hematogenous spread in contrast to typical lymphatic dissemination, and are likely to be hormone insensitive [1]. Relevant literature on metaplastic breast cancer with regards to the Singapore cohort of patients, are limited to single-institution case series, for which cohort numbers amount to less than 100 patients, while regionally, the Asia-Pacific MBC (AP‐MBC) Consortium amassed a series of about 350 patients [2, 3]. Furthermore, there are no established guidelines specific to the management of metaplastic breast cancer despite it being recognised as an independent negative prognostic indicator [4]. Due to its rarity, challenges in establishing diagnosis, and lack of established treatment guidelines, reported outcomes of metaplastic breast cancer are of interest. Hence, we propose a retrospective study on outcomes of metaplastic breast cancer in our institution. 

Aims: The primary aim will be to look at local and distant recurrence rates and overall survival, while secondary aim will be to study the impact of associated prognostic factors including stage of disease, hormone receptor status, and modalities of intervention. 

Hypothesis:  Local and distant recurrence rates and overall survival in higher grade metaplastic breast cancer subtypes are different from the rates and survival in non-metaplastic breast cancers.  Prognostic factors associated with the metaplastic subtype influence recurrence rates and survival.

Methodology: Retrospective study on outcomes of metaplastic versus non-metaplastic breast cancer in National Cancer Centre Singapore. 

References:
[1] Nelson, Rebecca A., et al. "Survival outcomes of metaplastic breast cancer patients: results from a US population-based analysis." Annals of surgical oncology 22.1 (2015): 24-31.
[2] Oon, Ming Liang, et al. "Cancer stem cell and epithelial–mesenchymal transition markers predict worse outcome in metaplastic carcinoma of the breast." Breast cancer research and treatment 150.1 (2015): 31-41.
[3] McCart Reed, Amy Ellen, et al. "Phenotypic and molecular dissection of metaplastic breast cancer and the prognostic implications." The Journal of pathology 247.2 (2019): 214-227.
[4] Lee H, Jung SY, Ro JY, et al. Metaplastic breast cancer: clinicopathological features and its prognosis. J Clin Pathol. 2012;65(5):441–446.

Joint Breast Cancer Registry Singapore