[210] Comparative Analysis of Ki67 Expression and Its Association with Axillary Nodal Metastasis in Patients with Triple Negative Versus Non-Triple Negative Breast Carcinomas

JS Han, KH Molberg, VR Sarode, LM Sutton, Y Peng. The University of Texas Southwestern Medical Center, Dallas, TX

Background: Triple negative (TN) breast carcinoma characterized by negativity for estrogen receptor (ER), progesterone receptor (PR) and Her2, is associated with shorter survival and a higher recurrence rate. Ki67 expression, a proliferation marker, is considered as a prognostic marker for patients with breast cancer. The aims of our study are to compare Ki67 expression in TN and non-TN breast carcinomas and to investigate an association between the Ki67 expression and axillary nodal metastasis in these tumors.
Design: Clinical characteristics and immunohistochemical tumor profiles were analyzed in 214 patients with high-grade invasive ductal carcinomas including 81 TN tumors and 133 non-TN tumors. Of the 133 non-TN tumors, 18 (13.5%) were ER-PR-Her2+, 18 (13.5%) were ER+PR±Her2+, and 97 (73%) were ER+PR± Her2-. The expression of Ki67 was compared between the TN and non-TN groups by one-way ANOVA with Turkey's post hoc test. In addition, a comparative analysis of the Ki67 expression in the TN tumors with nodal metastasis (n=32, 40%) versus the non-TN tumors with nodal metastasis (n=63, 47%) was conducted with unpaired t test.
Results: The TN tumors were larger than the non-TN tumors in size (3.18cm ± 0.45 vs. 2.31cm ± 0.21, p<0.05). The expression of Ki67 in the TN group was significantly higher than that in the non-TN group (63.7% ± 3.58 vs. 30.3% ± 2.37, p<0.0001). Of note, Ki67 expression in the TN tumors was significantly increased compared to the non-TN tumors that were ER+PR±Her2- (p<0.0001) or ER+PR±Her2+ (p<0.001), but there was no significant difference of the Ki67 expression between the TN tumors and the non-TN tumors that were ER-PR-Her2+. In addition, Ki67 expression in the TN tumors with nodal metastasis was significantly higher than that in the non-TN tumors with nodal metastasis (64.0% ± 6.02 vs. 31.9% ± 3.40, p<0.0001).
Conclusions: Our results indicate that TN breast tumors are associated with a significantly higher expression of Ki67 compared to non-TN tumors, which may contribute to the poorer prognosis in TN tumors. Hormonal receptor negativity rather than Her2 negativity appears to be the determining factor in significantly increased Ki67 expression in TN tumors. Furthermore, high Ki67 expression is more likely to be associated with axillary nodal metastasis in patients with TN tumors vs. non-TN tumors.
Category: Breast

Monday, March 22, 2010 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 17, Monday Morning


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