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Background: Recent studies have indicated that response to chemotherapy and the prognostic impact of a pathologic complete response (pCR) after neoadjuvant chemotherapy differ among breast cancer subtypes., Methods: Women with Stage I to III breast cancer treated with anthracycline and taxane-based neoadjuvant chemotherapy (four cycles of docetaxel every 3 weeks followed by four cycles of FEC every 3 weeks) between 2006 and 2011 were retrospectively analyzed. Trastuzumab was concurrently added to docetaxel for HER2-positive breast cancer. Expression of estrogen receptor (ER), progesterone receptor (PgR), HER2, and Ki67 was examined by immunohistochemistry in pre- and post-treatment specimens. Predictive factors for neoadjuvant chemotherapy and prognosis were analyzed by breast cancer subtype., Results: Of 64 patients, 30 (47 %) were ER-positive (ER+) HER2-negative (HER2-), including eight as luminal A (Ki67 labeling index (LI) <14 %) and 22 as luminal B (Ki67 LI ≥ 14 %) subtypes, 11 (17 %) were ER+ HER2-positive (HER2+), 12 (19 %) were ER-negative (ER-) HER2+, and 11 (17 %) were ER- HER2-. The clinical response rates were significantly higher in luminal B, ER+ HER2+, and ER- HER2+ subtypes compared with luminal A subtype. Patients whose tumors contained high Ki67 expression effectively responded to neoadjuvant chemotherapy. Ki67 LI was a predictive marker for pCR, and all patients whose tumors achieved pCR are currently disease-free. Furthermore, high Ki67 expression in post-treatment tumors was strongly correlated with poor disease-free and overall survival regardless of subtype., Conclusions: It is necessary to establish additional strategies to improve survival for patients whose residual tumors show high Ki67 expression after neoadjuvant chemotherapy.

Estrogen receptor (ER) is essential for estrogen-dependent growth, and its level of expression is considered a crucial determinant of response to endocrine therapy and prognosis in ER-positive breast cancer. On the other hand, the clinical role of progesterone receptor (PgR) in ER-positive breast cancer remains controversial, although testing of PgR by immunohistochemistry (IHC) has become routine. Recent studies indicated that plasma estradiol levels were related to the expression levels of estrogen-responsive genes in ER-positive breast cancer tissues in both pre- and postmenopausal women. In this study, we analyzed the expression levels of estrogen-responsive genes (PgR and TFF1), a progesterone-responsive gene (RANKL), ER-related genes (FOXA1 and GATA3), HER2, Ki67 and p53 in ER-positive, HER2-negative breast cancer tissues by IHC. Correlations between the expression levels of these molecular markers and clinicopathological factors, including prognosis, were compared between pre- and postmenopausal women. Serum levels of estrone, estradiol, progesterone, and testosterone were also measured. Expression levels of PgR, TFF1, RANKL, and GATA3 were significantly higher in premenopausal women than in postmenopausal women. Serum estradiol levels were positively correlated with Ki67 labeling index (LI) in premenopausal women, but not in postmenopausal women. High expression of FOXA1 and GATA3 was significantly associated with improved disease-free survival in premenopausal women, but not in postmenopausal women, whereas high expression of PgR and low expression of p53 were significantly correlated with the improved disease-free survival in postmenopausal women, but not in premenopausal women. Moreover, the best cutoff points of Ki67 LI for disease-free survival were 30 % for premenopausal women and 14 % for postmenopausal women. Expression levels of ER, TFF1, and RANKL were not associated with the disease-free survival in either pre- or postmenopausal women. Our results suggest that the mechanisms of development and estrogen-dependent growth of ER-positive breast cancer might differ according to menopausal status.

Aromatase inhibitors have played a central role in endocrine therapy for estrogen receptor (ER)-positive breast cancer in postmenopausal women. However, factors predictive of the efficacy of aromatase inhibitors, and prognostic factors, both for early and late recurrence in women treated with adjuvant aromatase inhibitors have not been identified. Whole genome analysis identified that a TP53 gene mutation exists in ER-positive breast cancers, although the frequency of TP53 gene mutation in luminal tumors is lower compared with basal-like or human epidermal growth factor receptor type 2 (HER2)-positive breast cancers. We examined expression of p53, as well as ER, progesterone receptor, HER2 and Ki-67 using immunohistochemistry in postmenopausal ER-positive breast cancer patients who were treated with aromatase inhibitors as adjuvant endocrine therapy. There were 53 (21%) tumors that contained 10% or more p53-positive cells. High p53 expression was positively correlated with tumor grade, HER2 score and Ki-67 expression. Significant association was observed between disease-free survival and high p53 expression in multivariate analysis (P < 0.0001). Compared with women without recurrence, women with early recurrence had significantly higher p53 expression (P < 0.0001), as did women with late recurrence (P = 0.037). The present study demonstrates that p53 accumulation is a strong predictor of both early and late recurrence in ER-positive breast cancer patients treated with aromatase inhibitors as adjuvant endocrine therapy. TP53 gene alteration might be a key biological characteristic of ER-positive breast cancer., (© 2013 The Authors. Cancer Science published by Wiley Publishing Asia Pty Ltd on behalf of Japanese Cancer Association.)