Response to Neoadjuvant Chemotherapy of Triple Negative Breast Cancer.
Authors: Tokudome N. , Ito Y. , Takahashi S. , Sugihara T. , Hosonaga M. , Iwasaki R. , Hattori M. , Fukuda T. , Mitsuhashi K. , Kobayashi K. , Taira S. , Saito Y. , Fukada I. , Ueki N. , Tsutsumi C. , Miyagi Y. , Iwase T. , Osako T. , Horii R. , Akiyama F. , Hatake K. 
Published: December 2010

Background: Triple negative breast cancer (TNBC) refers to breast cancers that don't express ER, PgR and HER-2, and several studies reported poorer clinical outcome than other groups. In spite of their poor outcome, on the basis of limited clinical data, TNBC patients demonstrated higher objective response rate and pathological complete response (pCR) rate than other subgroups with neoadjuvant chemotherapy. In this study, we evaluated the response to neoadjuvant chemotherapy of TNBC, reported the outcome of TNBC and other subgroups after neoadjuvant chemotherapy.Method: We analyzed the outcome and characteristics of patients treated with neoadjuvant chemotherapy using anthracycline and/or taxanes. Breast cancer subtypes are defined the following: Luminal A (ER+ and/or PgR+, HER2-), Luminal B (ER+ and/or PgR+, HER2+), HER2 (ER-, PgR-, HER2+), TN (ER-, PgR-, HER2-), Luminal A/B and HER2 subtypes were regarded as non-TNBC in this study.Result: Between 2000 and 2007, 639 breast cancer patients were treated with neoadjuvant chemotherapy at Cancer Institute Hospital. Clinical and immunohistochemical data was available on 596 patients. Median observation period was 1085 days (84-3382). In these cases, 111cases (18.6%) were defined as TNBC, and 485 cases (81.4%) were classified as non-TNBC. In each group, 28 and 138 cases (25.2% vs 28.5%), 35 and 132 cases (31.5% vs 27.2%), 48 and 215 cases (43.2% vs 44.3%) were treated with anthracycline (A), taxane (T), both A and T, respectively. Clinical complete response (cCR) rate and response rate (RR: CR + partial response (PR)) of TNBC were higher than of non-TNBC (cCR: 10.8% vs 2.7%, p=.0006) (RR: 66.7% vs 64.5%, p&lt;.0001), respectively. Despite the better cCR rates of TNBC, the clinical progressive disease (cPD) rate was higher than non-TNBC (15.3% vs 3.9%)(p&lt;.0001). With using only A or T regimen and the same treatment period, there was no difference in the cCR rate of TNBC between A and T (7.1% vs 2.9%)(p=.4274), but there was a difference in the cPD rate (0% vs 31.4%)(p=.0009). The pCR rate of TNBC and non TNBC was 9.0% and 2.5%, respectively (p=.001). The 3-yr disease free survival (DFS) rate was 78.4% with TNBC cases, and 84.7% with non-TNBC cases (p=.1027). However there was not difference in the 3-yr DFS between pCR and non-pCR groups of both TNBC (80.0% vs 78.2%, p=.8776) and non TNBC (91.7% vs 84.6%, p=.4994), respectively.Conclusions: With neoadjuvant chemotherapy, cCR and pCR rate of TNBC were higher than non-TNBC, but their cPD rate was also high. As for chemotherapy regimen, T might be less effective in treating TNBC. In this study, the total numbers of pCR cases were few, therefore pCR subsets might not contribute to good DFS. Despite standard neoadjuvant regimen usually including both A and T, half of the patients in this study underwent the chemotherapy with only A or T, due to our institutional previous study. TNBC tends to have worse prognosis, therefore more effective treatment would be required.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1102.