Expression of PD-L1 and prognosis in breast cancer: a meta-analysis

// Minghui Zhang 1, * , Houbin Sun 2, * , Shu Zhao 1, * , Yan Wang 3 , Haihong Pu 1 , Yan Wang 1 and Qingyuan Zhang 1 1 Department of Medical Oncology, Harbin Medical University Cancer Hospital, Harbin, 150081, China 2 Department of Intervention, Harbin Medical University Cancer Hospital, Harbin, 150081, China 3 Department of Medical Oncology, Heilongjiang Provincial Hospital, Harbin, 150000, China * These authors have contributed equally to this work Correspondence to: Qingyuan Zhang, email: zhma1965210@163.com Keywords: meta-analysis, prognosis, programed death-ligand 1, breast cancer Received: July 04, 2016     Accepted: January 31, 2017     Published: February 20, 2017 ABSTRACT The associations between programmed cell death ligand 1 (PD-L1) and the prognosis of various cancers have always been a research topic of considerable interest. However, the prognostic value of PD-L1 in breast cancer patients remains a controversial subject. We aimed to assess the association between PD-L1 protein expression and clinicopathological features and the impact of this relationship on breast cancer survival. We performed a systematic search of the PubMed, EMBASE, and Cochrane Library databases to determine the correlations among PD-L1 expression, clinicopathological features and overall survival (OS). A total of 5 studies containing 2,546 cases were included in the analysis. The combined hazard ratio (HR) and its 95% confidence interval (CI) for OS were 1.76 (95% CI 1.09–2.82; P =0.02) for patients with tumors exhibiting PD-L1 overexpression. The pooled odds ratios (ORs) indicated that PD-L1 expression was associated with positive lymph node metastasis, higher histological grades, estrogen receptor (ER)-negativity, and triple-negative breast cancer (TNBC). Our findings indicate that PD-L1 expression is a promising biomarker for the prognosis of breast cancer, and may be helpful to clinicians aiming to select the appropriate immunotherapy for breast cancer.