Prognostic Implications of PD-L1 Expression in Breast Cancer: Systematic Review and Meta-analysis of Immunohistochemistry and Pooled Analysis of Transcriptomic Data - Matikas, Alexios; Zerdes, Ioannis; Lövrot, John; Richard, François; Sotiriou, Christos; Bergh, Jonas; Valachis, Antonios; Foukakis, Theodoros (Clinical cancer research, 2019)