Clinicopathologic and Prognostic Factors of Triple Negative Breast Cancer in Saudi Arabia (Single Institution).
Authors: Abulkhair O. 
Published: December 2010

Abstract
IntroductionTriple negative breast cancer (TNBC) is a subtype of breast cancer that lacks the expression estrogen receptor (ER), progesterone receptor (PR) and HER2. This is uncommon subtype approximately representing 10 – 20% of breast cancers. The highest incidence was reported among premenopausal African American women. In Arab population, there were few available data suggesting similar incidence in the range of 10 – 12%. Recent studies have shown that TNBC are a heterogeneous group and may not always be associated with poor prognosis. The aim of this study is to determine the incidence, clinicopathological charateristics and evaluated prognostic factors in TNBC.Material and MethodsSixty-two cases of breast cancer were identified in our institution as TNBC out of 517 breast cancer cases reviewed from January 2001 to December 2008. The follow-up data was available for thirty cases of triple negative tumors. Thirty cases age and stage-matched were selected from the rest as control group. Slides were retrieved and reviewed, tumors graded according to Scarff-Bloom-Richardson grading system and tumor histologic type and features assessed. Clinical features and follow-up data were collected for all cases. Sections from selected paraffin blocks of the study tumors were stained by ER, PR, Her2/neu, p53 and CK5/6 following manufacture guidelines. The two groups were statistically analyzed by using Kaplan-Meier method for constructing survival curves and log-rank statistic for comparison of survival curves. The histopathological, immunohistochemical and clinical features were statistically analyzed by either Chi-square or Fisher's exact test using SPSS software.ResultsTriple negative tumors showed aggressive morphology that are more commonly high grade as compared to the control group (p=0.028). Overexpression of p53 immunostain was statistically significant more observed in the triple negative group (p=0.023) similarly for CK5/6 antibody (p&lt;0.001). No statistically significant difference in the patient's survival between the two groups. Young patients (&lt;40 year) with TNBC have statistically adverse outcome compared to the older patients with TNBC (p=0.04) and compared to non-TNBC (p=0.002). A subset of TNBC that are younger than 40 year and their tumor showed p53 overexpression and expressed basal cytokeratin (CK5/6) have aggressive outcome and more likely to develop brain metastasis (p&lt;0.001 and p=0.01 respectively).ConclusionThe incidence of TBNC in Saudi Arabia (12% - single institution) is similar to that described in the literature. These tumors are distributed in a wide range of age and showed no survival difference compared with age and stage-matched other types. However, a subset of these tumors that are seen in young, expressed basal cytokeratin CK5/6 and showed p53 immunostain overexpression tend to behave in aggressive fashion and more likely to develop brain metastatis compared to others. So, identifying those age group is of clinical importance.
Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3166.