[173] Triple-Negative Breast Cancers: Different Sensitivity to Chemotheray

YL Choi, E Oh, Y Kim, YH Park, EY Cho, JE Lee, JH Kim, SJ Nam, YH Lim, JH Yang, YK Shin, YC Hong. Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea; Seoul National University College of Pharmacy, Seoul, Korea; National Cancer Center, Goyang, Korea; Seoul National University College of Medicine, Seoul, Korea

Background: Triple-negative breast cancers (TNBCs) and basal-like breast cancers (BLBCs) have been known as poor outcome subtypes and lack of targeted therapy. Previous studies have shown conflicting results regarding the difference of prognostic significance between TNBCs and BLBCs. In this study, we aimed to characterize the prognostic features of TNBCs, in view of BLBCs and quintuple-negative breast cancers (QNBCs).
Design: Using immunohistochemistry-based tissue microarray analysis, we categorized 951 primary breast cancers into four or five subtypes according to the expression of ER, PR, HER2, and basal markers (CK5/6, EGFR).
Results: The results of this study showed that both TNBCs and BLBCs were associated with high histological and/or nuclear grades. When the TNBCs are divided into two subtypes by the presence of basal markers, the clinicopathologic characteristics of TNBCs were mainly maintained in the BLBCs. After multivariate analysis, the QNBCs had a worse prognosis than the BLBCs, and worst prognosis among all five subtypes. Interestingly, the patients with BLBCs without chemotherapy treatment had a shorter disease free and overall survival than any other subtypes including QNBCs. With adjuvant chemotherapy, BLBCs were not the worst prognostic group anymore, indicating that BLBCs appear to respond better than QNBCs among TNBCs. BLBCs showed chemotherapy response in both anthracycline based drug regimen and CMF chemotherapy. On the other hand, QNBCs did respond to CMF but not to anthracycline based drug.
Conclusions: The BLBC subtype is a subgroup of TNBCs that has significant chemotherapy benefit, especially anthracyclines but the QNBCs are not. The QNBCs comprise 5.5% to 13.5% of all breast cancers of the published study subjects and these results call for caution in the identification of subgroup of patients for therapeutic classification.
Category: Breast

Tuesday, March 23, 2010 9:30 AM

Poster Session III # 48, Tuesday Morning


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