Clinicopathological Study of Epithelial Metaplastic Breast Cancer

Introduction: Metaplastic breast cancer (MBC) is a rare pathological type with an incidence rate of not more than 1%, and has been reported to be often detected after its progression and highly malignant with a high proportion of triple negative type tumors, with poor outcomes as compared to IDC [1] [2] [3]. We analyzed clinicopathological characteristics of patients who underwent surgery for epithelial MBC at our department. Patients and Methods: From January 2000 to March 2014, a total of 2120 patients underwent surgery for breast cancer, and MBC was diagnosed in 15 of these patients. Fourteen of the 15 had epithelial MBC and were included in this study. The present study compared clinopathological characteristics of MBC with those of IDC of triple negative type (TN type group) and IDC of non-triple negative type (IDC group). Results: Breast conserving surgery was performed in 7 patients with MBC (50%), a proportion clearly lower than the 64.3% in the IDC group. The mean tumor size was 3.8 cm, which was greater than the 2.13 cm in the TN type group and the 1.7 cm in the IDC group. About nuclear grade, the proportion of grade III was 57.1%, markedly higher than the 38.6% in the TN type group and the 12.6% in the IDC group. All patients were estrogen receptor (ER) and progesterone receptor (PgR) negative; 11 patients were TN type tumors and 3 were HER2 type. Conclusion: We studied patients who underwent surgery for epithelial MBC. The examined cases showed clinopathological characteristics of the disease, including large tumors with a highly malignant nature at the initial detection, higher Ki-67 levels, ER and PgR negativity (all cases), mostly TN type, and a high recurrence rate.