Genetic polymorphisms in the matrix metalloproteinase 12 gene (MMP12) and breast cancer risk and survival: the Shanghai Breast Cancer Study

Table 1 Comparisons of participants with MMP12 genotype information.

Participant characteristics	Cases^a (N = 1,129)	Controls^a (N = 1,229)	P ^b
Demographic factors
Age (years)	47.6 ± 8.0	47.2 ± 8.7	0.20
Education (% high school or more)	43.4%	43.1%	0.89
Reproductive risk factors
Age (years) at menarche	14.5 ± 1.6	14.7 ± 1.7	<0.01
Age (years) at menopause^c	48.2 ± 4.7	47.5 ± 4.9	0.04
Age (years) at first live birth^d	26 ± 4.1	26.0 ± 3.8	<0.01
Other risk factors
Breast cancer among first-degree relatives (%)	3.4	2.4	0.11
Ever had breast fibroadenoma (%)	9.7	5.1	<0.01
Body mass index (kg/m²)	23.5 ± 3.4	23.2 ± 3.4	0.03
Waist-to-hip ratio	0.81 ± 0.06	0.80 ± 0.06	<0.01
Physically active during past 10 years (%)	19.3	25.7	<0.01

^aValues are presented as means ± standard deviations unless otherwise noted.
^bCalculated from the t-test for continuous variables and the χ² test for categorical variables. ^cAmong postmenopausal women. ^dAmong parous women.

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