Table 6.

MR results of the causal effect of ER-negative BC on MMP-1.

Exposure	Outcome	No. of SNPs	Method	β	P value	Heterogeneity		Pleiotropy
						Cochrane's Q	P	P
ER-negative BC (ieu-a-1128)	MMP1	37	MR Egger	0.06	0.35	35.13	0.46	0.39
			Weighted median	0.03	0.37
			Inverse variance weighted	0.01	0.63	35.81	0.48
			Simple mode	− 0.06	0.40
			Weighted mode	0.04	0.54
ER-negative BC (ieu-a-1135)	MMP1	14	MR Egger	− 0.04	0.71	16.86	0.15	0.74
			Weighted median	− 0.001	0.98
			Inverse variance weighted	0.005	0.87	17.17	0.19
			Simple mode	− 0.03	0.64
			Weighted mode	0.03	0.66
ER-negative BC (ieu-a-1136)	MMP1	7	MR Egger	0.009	0.96	5.48	0.36	0.31
			Weighted median	0.05	0.28
			Inverse variance weighted	0.02	0.61	5.48	0.48
			Simple mode	0.08	0.33
			Weighted mode	0.09	0.35
ER-negative BC (ieu-a-1166)	MMP1	8	MR Egger	0.17	0.54	8.01	0.24	0.68
			Weighted median	0.02	0.68
			Inverse variance weighted	0.005	0.89	8.56	0.29
			Simple mode	0.10	0.32
			Weighted mode	0.10	0.31

BC Breast cancer; ER Estrogen receptor; MMP Matrix metalloproteinases; MR Mendelian randomization; SNP Single nucleotide polymorphisms.