Estrogen receptor (ER)-positive and human epidermal growth factor receptor 2 (HER2)-negative patients account for 70% of early-stage invasive breast cancer. In current clinical practice, these patients receive either endocrine therapy or chemo-endocrine therapy as adjuvant treatment.
The 2017 St. Gallen consensus meeting recommend that adjuvant treatment for ER-positive; also HER2-negative breast cancer should be escalate or de-escalate base on the molecular subtype, patient outcome, and side effects of the adjuvant treatment. According to several biomarkers, such as the expression of progesterone receptor (PgR) and the Ki67 labeling index (LI), and several genomic tests; so ER-positive and HER2-negative breast cancer is classify into the luminal A-like, luminal B-like , and intermediate types.
Adjuvant endocrine therapy,
The 2017 St. Gallen consensus meeting suggest that luminal A-like breast cancer; which treat with adjuvant endocrine therapy, and luminal B-like breast cancer should be treat with adjuvant chemo endocrine therapy, respectively. However, the most appropriate treatment for the intermediate type, which accounts for 50% of ER-positive and HER2-negative breast cancer cases, remains undetermined.
Moreover, several biomarkers have reveal the usefulness to avoid chemotherapy in the low-risk group. However, the usefulness of these biomarkers to predict response to chemotherapy in the high-risk group has not been assessed. Therefore, further investigation of biomarkers to determine the escalation of chemotherapy and/or molecular target therapy in ER-positive and HER2-negative breast cancer patients is warranted.
In the present study, they evaluate the Ki67 LI, expression of PgR and cyclin D1 (CCND1), and level of ER activity in post-menopausal ER-positive and HER2-negative patients at the pretreatment and end of neoadjuvant endocrine therapy alone stages. In addition, the relationship of these factors with pathological response after completing the neoadjuvant chemo-endocrine therapy was assessed.
Design of chemotherapy
For many years, factors that could clearly define favorable and poor prognosis; which have consider in the design of chemotherapy indication studies; so addressing early-stage ER-positive and HER2-negative breast cancer. In the 2017 St. Gallen consensus meeting, it was recommend; so that the multigene assay is the most effective method of evaluation to determine indications; its for adjuvant chemotherapy although immunostaining of Ki67 or PgR have also evaluate as effective methods.
In conclusions, the expression of CCND1 and ER activity; so following neoadjuvant endocrine therapy may be associate with the efficacy; so of chemo-endocrine therapy in post-menopausal patients with ER-positive; also HER2-negative breast cancer. Certain patients in this group cannot be clearly determine as Luminal A-like or Luminal B-like types.
In such cases, it may be necessary to consider the escalation of subsequent treatment through combination with chemotherapy or a new molecular targeted drug. This refers to the degree of cell cycle activation and level of ER-activity after neoadjuvant endocrine therapy with an aromatase inhibitor.