Abstract P3-10-38: Histopathological Subclassification of Triple Negative Breast Carcinoma Using Prognostic Scoring System

Abstract Purpose: Triple negative breast carcinoma (TNBC) is currently being required to be classified pluralistically in order to provide the most appropriate therapy to the patients. We attempted to subclassify TNBC cases into subgroups based on clinical outcome or prognosis of the patients with TNBC using archival specimens. Materials and Methods: We analyzed 102 Japanese cases of invasive TNBC who underwent surgery between January 1998 and December 2007. The clinicopathological factors and clinical information of these patients were retrospectively retrieved from charts of the patients. Immunohistochemical staining was performed for estrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor receptor 2 (HER2), epidermal growth factor receptor 1 (EGFR1), CK5/6, Ki-67 and CD31 for microvessel density (MVD). Results: Median follow-up time of the patients was 68.5 months. Multivariable analysis demonstrated that the pathologic node status was the most significantly associated with relapse-free survival (RFS) and breast cancer-specific survival (BCSS) of the patients. Pathological tumor size, basal-like type, Ki-67 labeling index (LI) and MVD were also independently associated with RFS and BCSS. Based on these results, we devised the Risk Score system reflecting Hazard ratios (HRs) of these prognostic factors above. Multivariate analysis and the Risk Score for TNBC patients. With this system, TNBC patients in this study were classified into three subgroups; patients with score 0-3 are in low risk group, score 4-7 in intermediate risk group and score 8- in high risk group. These three groups had statistically significant differences for risk of relapse and breast cancer-specific death, respectively. Conclusions: We propose the Risk Score system, which incorporated pathologic nodal status, size of the primary tumor, the presence or absence of basal-like features, Ki67 LI and MVD of the patients in order to predict postoperative clinical course of the Japanese patients with TNBC. Such a classification which can be performed in diagnostic pathology laboratory can be useful as a decision-making tool for triple negative patients. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-10-38.