title: Prognostic Value of PD-L1 in Breast Cancer: A Meta-Analysis.
abstract: Programmed cell death 1 ligand 1 (PD-L1) is a promising therapeutic target for cancer immunotherapy. However, the correlation between PD-L1 and breast cancer survival remains unclear. Here, we present the first meta-analysis to investigate the prognostic value of PD-L1 in breast cancer. We searched Pubmed, Embase, and Cochrane Central Register of Controlled Trials databases for relevant studies evaluating PD-L1 expression and breast cancer survival. Fixed- and random-effect meta-analyses were conducted based on heterogeneity of included studies. Publication bias was evaluated by funnel plot and Begg's test. Overall, nine relevant studies with 8583 patients were included. PD-L1 overexpression was found in 25.8% of breast cancer patients. PD-L1 (+) associated with several high-risk prognostic indicators, such as ductal cancer (p = 0.037), high tumor grade (p = 0.000), ER negativity (p = 0.000), PR negativity (p = 0.000), HER2 positivity (p = 0.001) and aggressive molecular subtypes (HER2-rich and Basal-like p = 0.000). PD-L1 overexpression had no significant impact on metastasis-free survival (HR 0.924, 95% CI = 0.747-1.141, p = 0.462), disease-free survival (HR 1.122, 95% CI = 0.878-1.434, p = 0.357) and overall specific survival (HR 0.837, 95% CI = 0.640-1.093, p = 0.191), but significantly correlated with shortened overall survival (HR 1.573, 95% CI = 1.010-2.451, p = 0.045). PD-L1 overexpression in breast cancer associates with multiple clinicopathological parameters that indicated poor outcome, and may increase the risk for mortality. Further standardization of PD-L1 assessment assay and well-controlled clinical trials are warranted to clarify its prognostic and therapeutic value.
authors.affiliation: Department of Breast Surgery, Peking Union Medical College Hospital, Beijing, China.
authors.forename: Changjun
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Dermatology, University of California, San Francisco, California.
authors.forename: Hanjiang
authors.initials: H
authors.lastname: Zhu
authors.affiliation: Department of Breast Surgery, Peking Union Medical College Hospital, Beijing, China.
authors.forename: Yidong
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Breast Surgery, Peking Union Medical College Hospital, Beijing, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Mao
authors.affiliation: Department of Breast Surgery, Peking Union Medical College Hospital, Beijing, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Lin
authors.affiliation: Department of Breast Surgery, Peking Union Medical College Hospital, Beijing, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Pan
authors.affiliation: Department of Breast Surgery, Peking Union Medical College Hospital, Beijing, China.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Breast Surgery, Peking Union Medical College Hospital, Beijing, China.
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Xu
authors.affiliation: Department of Breast Surgery, Peking Union Medical College Hospital, Beijing, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Huang
authors.affiliation: Department of Breast Surgery, Peking Union Medical College Hospital, Beijing, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Sun
mesh_terms: D015415:Biomarkers / Q000378:metabolism*; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D005260:Female; D006801:Humans; D011379:Prognosis; D061026:Programmed Cell Death 1 Receptor / Q000378:metabolism*
chemical_list: D015415:Biomarkers; C105992:PDCD1 protein, human; D061026:Programmed Cell Death 1 Receptor
keywords: breast cancer; prognostic value; programmed death receptor 1; programmed death receptor 1 ligand 1; survival