Published in:
01-03-2015 | Original Article
Prognostic significance of pathologic complete response and Ki67 expression after neoadjuvant chemotherapy in breast cancer
Published in: Breast Cancer | Issue 2/2015
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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.