Expression Significance of Estrogen Receptor ER-α36 in Breast Cancer Treated by Chemotherapy: A Meta-Analysis

Abstract

Estrogen receptor (ER) is a molecular marker and target for diagnosing and treating breast cancer (BC). ER-α36, a novel estrogen receptor subtype, involved in the proliferation, differentiation, metastasis, and invasion of tumor cells. It is closely linked to the progression of various cancers. Therefore, studying ER is of high significance in treating BC. In this study, we will investigate the changes in the expression level of ER-α36 in patients with BC treated by chemotherapy through meta-analysis, so as to evaluate the clinical value of ER-α36 in the prognosis of BC treated by chemotherapy. English databases such as PubMed, Web of Science, Embase, and The Cochrane Library were searched to retrieve the articles published from the establishment of the database to April 2023. The keywords included chemotherapy, neoadjuvant chemotherapy, breast cancer, estrogen receptor alpha, and ER-α36. Five suitable studies, encompassing 636 patients, were ultimately selected. The meta-analysis results revealed that, following the chemotherapy, the analysis of ER-α36 positive cases yielded an Odds Ratio (OR) of 0.42, a 95% confidence interval (CI) of 0.28-0.64 (Z = 4.00, P < 0.0001). Additionally, the analysis of cases exhibiting remission in BC demonstrated an OR of 2.22 (95% CI = 1.40-3.50, Z = 3.40, P = 0.0007). Compared to patients receiving single chemotherapy agents or those untreated with chemotherapy, the combined use of multiple chemotherapy drugs can significantly reduce the levels of ER-α36 in BC patients, enhancing the remission rate of BC. ER-α36 can serve as a critical indicator for assessing the prognosis of BC following chemotherapy.

Keywords: Breast cancer; Chemotherapy; ER-α36; Estrogen receptor.