Clinical Study of Adjuvant Therapy on Post-menopausal Women With Breast Cancer Under the Guidance of the Results of Preoperative Endocrinotherapy

In the decision-making process of a systemic adjuvant therapy for ER-positive/HER2-negative breast cancer, to avoid adjuvant chemotherapy is an attractive but hard choice. On one hand, the result of tamoxifen endocrine therapy combined with adjuvant chemotherapy is superior to tamoxifen endocrine therapy alone for ER-positive breast cancer patients; on the other hand, the benefit that adjuvant chemotherapy provides to breast cancer with high hormone receptor expression is not clear and the tolerance of chemotherapy is much lower than that of endocrinotherapy. St. Galen consensus on adjuvant therapy for early breast cancer recommends adopting simple endocrinotherapy and avoiding adjuvant chemotherapy for medium- and low- risk breast cancer with hormone receptor highly expressed. However, the results of study P024 and IMPACT suggest that hormone receptor expression is insufficient to predict the effect of endocrinotherapy. At present, the proven clinical value of neoadjuvant endocrinotherapy is to assist surgery. Consensus recommends neoadjuvant endocrinotherapy for the patients with postmenopausal breast cancer who plan to receive simple adjuvant endocrinotherapy. The current study results show that neoadjuvant endocrinotherapy may be used as an experimental treatment platform, i.e., it can predict the results of adjuvant endocrinotherapy through comprehensive analysis of multiple indexes of the surgery samples after neoadjuvant endocrinotherapy. By using P024 and IMPACT samples, Ellis et al studied the relation between survival and the test results of surgery samples after neoadjuvant endocrinotherapy, and obtained PEPI (the preoperative endocrine prognostic index). They have preliminarily proved that the PEPI score is relative to RFS (relapse-free survival) of postmenopausal ER-positive breast cancer treated with simple endocrinotherapy and to BCSS (breast cancer-specific survival). A retrospective study，performed by breast prevention and treatment center in Peking University Cancer Hospital，shows that RFS in PEPI score ≤ 1 group is superior to the PEPI \> 1 group after 16 weeks of neoadjuvant endocrinotherapy(p = 0.037), and RFS in effective group (Miller\&Payne G1G2G3) is better than that in ineffective group (p=0.001) in terms of pathological evaluation. The objective of this study is to prospectively verify the relation of efficacy of neoadjuvant hormonal therapy, and preliminarily explore the clinical value of complementary adjuvant chemotherapy to predict poor prognosis malignant breast cancer after neoadjuvant endocrinotherapy.