A. the CSS curves in breast cancer patients with only one distant metastasis site according to different BCS (HR+/HER2-: χ2=29.70, P<0.001; HR+/HER2+:χ2=3.610, P=0.308; HR-/HER2+:χ2=8.461, P=0.037; HR-/HER2-:χ2=5.385, P=0.147). B. the CSS curves in breast cancer patients with two distant metastasis sites according to different BCS (HR+/HER2-:χ2=33.12, P<0.001; HR+/HER2+:χ2=11.49, P=0.009; HR-/HER2+:χ2=0.260, P=0.967; HR-/HER2-:χ2=4.347, P=0.226). C. the CSS curves in breast cancer patients with three distant metastasis sites according to different BCS (HR+/HER2-: χ2=0.494, P=0.482; HR+/HER2+: χ2=0.990, P=0.320; HR-/HER2+: χ2=1.212, P=0.271; HR-/HER2-: χ2=0.313, P=0.576). D. the CSS curves in breast cancer patients with four distant metastasis sites according to different BCS (χ2=4.918, P=0.178).