P4-09-33: The Prognostic Significance of Metaplastic Carcinoma of the Breast – A Comprehensive Comparison Study with Common Breast Cancers.

Abstract

Abstract Purpose : Metaplastic carcinoma of the breast (MCB) is a rare histological subtype of breast cancer with incidence less than 1%. Due to its rarity, the clinical characteristics and prognostic significance of MCB compared with other common breast cancer, such as infiltrating ductal carcinoma (IDC) and infiltrating lobular carcinoma (ILC) are not clear and controversial between different reports. We performed a multi-institutional cases collective comparison study to evaluate the clinical characteristics and prognostic status with IDC and ILC. Materials and methods : Cases of MCB were enrolled from 4 medical centers in Taiwan. Forty-five MCB patients combined with 1777 IDC and 53 ILC patients from cancer registry database of Changhua Christian Hospital (CCH) comprised the current study. The patients’ demographic data, tumor characteristics and prognosis of MCB were analyzed and compared with IDC, and ILC. To further clarify the prognostic difference between MCB and IDC, a case control analysis was performed to minimize the effect of tumor size, lymph node status and other clinicopathologic factors. The disease free survival (DFS) and overall survival (OS) between groups were compared. Results : Compared with IDC, MCB was associated with older age, larger tumor size, lesser lymph node positive rate, higher distant metastasis, higher tumor grade, lower ER positive tumor, and higher triple negative breast cancer subtype (TNBC). Compared with IDC, MCB was associated with worse OS (p=0.031), but no difference in DFS (p=0.071). While MCB was not statistically different from ILC in both DFS and OS (p=0.132 and 0.289, respectively). To eliminate the influence of other prognostic factors, 135 cases controlled IDC with comparable clinicopathologic parameters were enrolled to compare with those 45 MCB patients. Compared with cases controlled IDC group, the MCB patients remained showed poorer OS (p=0.040), but not different in DFS (p=0.439). Conclusion : MCB was associated with poorer OS compared with IDC, and this poorer prognosis was related to tumor behavior rather than clinicopathologic factors. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-09-33.