Baseline characteristics in cases and controls.

Features of primary tumors of cases and controls. Number (%), Mean (± standard deviation) of tumor size and expression of receptors. The basic status of the estrogen receptor (ER), progesterone receptor (PR), cell proliferation marker Ki-67 (ki67), and human epidermal growth factor receptor 2 (HER2) play a crucial role in molecular subtypes classification of breast cancer. Student’s t-test showed significant difference for all the observed variables between cases and controls, excluding size. Fisher’s exact test did not show significant difference for HER2+. CI: confidence interval.

病例组与对照组的原发肿瘤特征统计方式如下：受体表达情况以例数（百分比）呈现，肿瘤大小以均值（±标准差）呈现。雌激素受体（estrogen receptor, ER）、孕激素受体（progesterone receptor, PR）、细胞增殖标志物Ki-67（Ki-67）以及人表皮生长因子受体2（human epidermal growth factor receptor 2, HER2）的基础状态，在乳腺癌分子亚型分类中具有关键作用。学生t检验（Student’s t-test）结果显示，除肿瘤大小外，病例组与对照组间所有观测变量均存在显著差异。费希尔精确检验（Fisher’s exact test）结果显示，病例组与对照组的HER2阳性（HER2+）情况无显著差异。CI即置信区间（confidence interval）。