Purpose: Metaplastic carcinomas of the breast (MCBs) are rare diseases. The aim of this study is to evaluate the clinicopathologic characteristics of MCBs and to compare them with those of infiltrating ductal carcinoma (IDC).
Methods: Thirty-eight patients who underwent surgery at Seoul National University Hospital from May 1982 to December 2002 were retrospectively analyzed on the basis of the medical records and the pathology reports. These patients were compared with 3578 IDC patients that we experienced during the same period.
Results: The histologic subtypes of MCBs were 7 squamous, 6 matrix-producing, 7 sarcomatous, 4 mixed, 1 osteogenic, and 13 unclassified tumors. The mean tumor size was 4.4±3.1 cm. The operations’ methods were a modified radical mastectomy in 26 patients, breast conserving surgery in 11 patients and only an incisional biopsy in one patient. Lymph node metastases and distant metastases were detected in 11 (29.7%) and 5 (13.2%) patients respectively. Lymph node metastases of MCBs were significantly lower than that for the IDC group (p = 0.030). Otherwise, the distant metastases were significantly higher than that of the IDC group (p = 0.019). The MCBs group also showed a significantly higher nuclear grade and histologic grade than did the IDC group (p = 0.001, p = 0.001). Estrogen receptor and progesterone receptor positivity was 5.3% and 5.3% respectively, which were significantly lower than that for the IDC group (p < 0.001, p = 0.002). The overall 5 year survival rate was 65% and the 5 year disease-free survival rate was 68%. After exclusion of patients with distant metastasis, the overall survival rates were not significantly different between the two groups (p = 0.291).
Conclusion: MCB is a rare pathological entity. Compared with IDC, MCB displays a larger size, less lymph node metastasis, more distant metastasis, a higher histologic grade, and less hormone receptor expression. MCB has a poorer overall survival rate, which is probably due to its frequent distant metastasis. (J Breast Cancer 2005;8:59-63)
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