Metaplastic Breast Cancer- A Rare Disease

Management algorithms for invasive and non-invasive ductal and lobular breast carcinomas are well-established. Because of their very nature, rare histologic types of primary breast cancers are not represented in practice guidelines and thus present a challenge to the practicing clinician who must make recommendations for surgical treatment, axillary staging, and adjuvant therapy, as well as counsel patients as to their expected disease course and prognosis.

Abstract from: Treatment and Prognosis of Rare Breast Cancers
The first individual case reorts of MBC were published in the 1960s and 1970s, but it was not until the late 1980s that this rare subtype of breast cancer began to be characterized. Between 1989 and 1990, Wargotz et al. described five distinct histological subtypes of MBC: matrix-producting carcinoma, spindle cell carcinoma, carcinosar-coma, squamous cell carcinoma of ductal origin, and metaplastic carcinoma with osteoclastic giant cells. Because both the epithelial and mesenchymal components of MBC have been shown to be cytokeranin-positive, it has been hypothesized that the histologic findings in MBC are due to metaplastic transformation of carcinoma cellsMBC was assigned a unique diagnosis code in 2000, which has allowed investigators to study the clinical behaviou of this rare entity, comprimising 0.25% of all breast cancers, through th euse of large registry dada. Concordant results were obtained from two large studies of MBC: 892 cases in the National Cancer Database between 2001 and 2003, and 1011 cases in the Surveillance, Epidemiology, and End Results (SEER) dataset between 2001 and 2010. Compared with IDC, these large studies have shown that patients with MBC generally present with larger tumors that are more likely to be poorly differentiated and triple-negative. Although MBC has a lower incidence of nodal metastasis than IDC, MBC is associated with a poorer prognosis. This was illustrated by a matched case-control analysis that showed lower disease-specific and overall survival at 5 years for MBC versus IDC. The most marked survival difference is seen in the stage III patients, which is attributed to the decreased efficacy of systemic therapies for MBC versus the triple-negative IDC.The National Cancer Database and SEER studies have shown that patients with MBC are treated in a similar fashion as those with IDC. More patients with MBC were found to undergo mastectomy instead of breast-conserving approaches, likely due to the larger average size of the MBC at presentation. In the SEER study, although radiation therapy was found to have been administered to fewer patients with MBC versus IDC (48 vs. 54%), the use of adjuvant radiation thereapy was shown to be independently associated with improved survivial in patients with MBC. In another SEER study of 1501 patients with MBC, radiation therapy was found to be associated iwth a disease-free [hazard ratio (HR) 0.74] and overall survivial (HR 0.64) benefit. Because of the predominantly triple-negative receptor profile of MBC, the majority of these patients receive systemic therapy; unfortunately though, multiple reports have shown that MBC is relatively resistant to a variety of chemotherapeutic agents.Copyright Society of Surgical Oncology 2015
Published Online: 11 August 2015
Terando, A.M., Agnese, D.M. & Holmes, D.R. Ann Surg Oncol (2015)
PMID: 26259751 DOI: 10.1245/s10434-01504748-0Complete Paper