Lambe Institute for Translational Research, National University of Ireland, Galway, Ireland.
Department of Surgery, Galway University Hospitals, Galway, Ireland.
Br J Surg. 2021 Jun 22;108(6):622-631. doi: 10.1093/bjs/znab103.
Uncertainty exists regarding the clinical relevance of programmed cell death ligand 1 (PD-L1) expression in breast cancer.
A systematic review was performed in accordance with PRISMA guidelines. Observational studies that compared high versus low expression of PD-L1 on breast cancer cells were identified. Log hazard ratios (HRs) for disease-free and overall survival and their standard errors were calculated from Kaplan-Meier curves or Cox regression analyses, and pooled using the inverse-variance method. Dichotomous variables were pooled as odds ratios (ORs) using the Mantel-Haenszel method.
Sixty-five studies with 19 870 patients were included; 14 404 patients were classified as having low and 4975 high PD-L1 expression. High PD-L1 was associated with achieving a pathological complete response following neoadjuvant chemotherapy (OR 3.30, 95 per cent confidence interval 1.19 to 9.16; P < 0.01; I2 = 85 per cent). Low PD-L1 expression was associated with human epidermal growth factor receptor 2 (OR 3.98, 1.81 to 8.75; P < 0.001; I2 = 96 per cent) and luminal (OR 14.93, 6.46 to 34.51; P < 0.001; I2 = 99 per cent) breast cancer subtypes. Those with low PD-L1 had favourable overall survival rates (HR 1.30, 1.05 to 1.61; P = 0.02; I2 = 85 per cent).
Breast cancers with high PD-L1 expression are associated with aggressive clinicopathological and immunohistochemical characteristics and are more likely to achieve a pathological complete response following neoadjuvant chemotherapy. These breast cancers are, however, associated with worse overall survival outcomes.
程序性死亡配体 1（PD-L1）在乳腺癌中的表达与临床相关性尚不确定。
按照 PRISMA 指南进行系统评价。确定了比较乳腺癌细胞中 PD-L1 高表达与低表达的观察性研究。从 Kaplan-Meier 曲线或 Cox 回归分析中计算无病生存和总生存的对数危险比（HR）及其标准误差，并使用倒数方差法进行合并。使用 Mantel-Haenszel 方法将二项变量合并为优势比（OR）。
共纳入 65 项研究，包含 19870 例患者；其中 14404 例患者被归类为低 PD-L1 表达，4975 例患者为高 PD-L1 表达。高 PD-L1 与新辅助化疗后获得病理完全缓解相关（OR 3.30，95%置信区间 1.19 至 9.16；P<0.01；I2=85%）。低 PD-L1 表达与人类表皮生长因子受体 2（OR 3.98，1.81 至 8.75；P<0.001；I2=96%）和管腔（OR 14.93，6.46 至 34.51；P<0.001；I2=99%）乳腺癌亚型相关。低 PD-L1 表达的患者总生存情况较好（HR 1.30，1.05 至 1.61；P=0.02；I2=85%）。
高 PD-L1 表达的乳腺癌与侵袭性临床病理和免疫组织化学特征相关，且更有可能在新辅助化疗后获得病理完全缓解。然而，这些乳腺癌的总生存结局较差。
