[264] Six1 Expression in Triple Negative Breast Carcinoma: Correlation with Prognostic Parameters and Outcome.

Harold C Sullivan, Amy Adams, Gabriela M Oprea, Andrew J Page, Cohen Cynthia. Emory University School of Medicine, Atlanta, GA

Background: Homeobox genes give rise to transcription factors that play an essential role in embryologic development. Misexpression of these genes is implicated in the development of cancers. One homeobox gene, homeobox 1 homolog homeoprotein, known as Six1, is overexpressed in hepatocellular, ovarian, and breast cancer. Six1 induces epithelial-mesenchymal transition in breast carcinoma cell lines and may be involved in metastasis. Patients with triple negative breast carcinoma (TNBrCa) have poorer prognostic factors and poorer survival compared to those with breast cancers that express hormones and/or HER2. TNBrCa demonstrate a propensity to metastasize to visceral organs. We studied TNBrCa for Six1 expression in relation to the aggressive nature and metastatic tendency of TNBrCa.
Design: 130 invasive TNBrCa were immunostained for Six1 in tissue microarrays (TMA) with 2 1mm cores of each carcinoma. Clinicopathologic criteria (age, tumor size, grade, lymph node status, angiolymphatic invasion) and survival data were obtained. Carcinoma TMAs were stained for CK5/6, CK7, CK8, CK14, CK18, CK19, p53, p63, topoisomerase, androgen receptor, Ki-67, c-kit, EGFR, p-cadherin, vimentin, and CD44. Clinicopathologic criteria, marker expression, and outcome (overall and recurrence free survival, dead of disease, recurrence) were compared in Six1-positive and -negative tumors.
Results: Six1 was present in 89 (69%) TNBrCa, 55 (74%) being African American and 34 (61%) Caucasian (p=0.098).

Clinicopathologic characteristics, marker expression, and outcome of TNBrCa in Six1-positive and -negative patients
Characteristic/markerSix1-positive no. (%)Six1-negative no. (%)P-value
Tumor size (cm)
Grade III72/97 (74)25/97 (26)0.047
Lymphovascular invasion32/88 (36)8/39 (21)0.076
Metastases32/79 (41)8/36 (22)0.056
Topoisomerase68/86 (79)22/35 (63)0.064
Ki-6773/85 (86)19/37 (51)<0.001

Other clinicopathologic criteria, markers, and outcomes were not significantly different in both populations.
Conclusions: Six1 is present in almost 70% of TNBrCa. Six1-positive TNBrCa show poor prognostic parameters (large tumor size, high grade, high Ki-67 proliferation) compared to Six1-negative carcinomas. Additionally, a strong tendency to lymphovascular invasion and metastases was noted in Six1-positive tumors.
Category: Breast

Monday, February 28, 2011 1:00 PM

Poster Session II # 65, Monday Afternoon


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