[192] Comparative Analysis of p53 Expression in Triple Negative Versus Non-Triple Negative Invasive Breast Cancers

JS Han, KH Molberg, V Sarode, AV Gavino, Y Peng. UT Southwestern, Dallas, TX

Background: Triple negative (TN) breast cancers characterized by negativity for estrogen receptors (ER), progesterone receptors (PR) and Her2, lack the benefit of specific therapy that targets these proteins and are associated with shorter survival and a higher recurrence rate. To improve the prognosis of TN tumors, a new effective therapeutic strategy is needed. Recent studies suggested that p53 status might have a different predictive value for efficacy of anthracycline/alkylating agents- based chemotherapy regimen between TN and non-TN breast cancers. Therefore, we compared expression of p53 between TN and non-TN tumors in patients with grade II or grade III invasive ductal carcinoma.
Design: Clinical characterizes and tumor profiles were analyzed in 58 patients (24 TN tumors and 34 non-TN tumors). Of the 34 non-TN tumors, 18% were ER-PR-Her2+, and 82% were ER+ or PR+ or both ER+ PR+. The expression of p53 was compared between the TN and non-TN groups by one-way ANOVA with post hoc test, and also examined in core-needle biopsies and subsequent resection specimens.
Results: The TN tumors were larger than the non-TN tumors in size (p<0.03), and appeared to have a higher rate of axillary nodal metastasis than the non-TN tumors (75% vs. 68%, p=0.57). The expression of p53 in TN group was significantly higher than that in the non-TN group (p<0.0001). Moreover, the p53 expression in the TN tumors was significantly increased compared to the non-TN tumors that were ER+ or PR+ or both ER+PR+ (p<0.001), while there was no significant difference of the expression of p53 between the TN tumors and the non-TN tumors that were ER-PR-Her2+. Tumors showed a similar expression of p53 between core biopsies and resection specimens on the same patients in both the TN and non-TN groups.
Conclusions: Our results indicate that TN breast tumors are associated with a higher expression of p53 compared to non-TN tumors, which may contribute to TN tumors having a poorer prognosis. Hormonal receptor status rather than Her2 status appears to play an important role in significantly increased p53 expression in TN tumors. The expression of p53 in core-needle biopsies can be predictive of its status in resection specimens in both the TN and non-TN tumors.
Category: Breast

Monday, March 9, 2009 9:30 AM

Poster Session I Stowell-Orbison/Autopsy Award # 33, Monday Morning