Table 1. Distributions of select variables in breast cancer patients and healthy controls.

Characteristics		Cases	Controls	p value
Number		183	195
Age (mean ± SD)		46.4 ± 9.38	45.35 ± 6.89	0.218a
BMI, kg/m2 (mean ± SD)		23.08 ± 3.00	22.53 ± 2.55	0.056a
Menopause status				0.716b
	Premenopausal	115	119
	Postmenopausal	68	76
Age of menarche	≤ 12	25
	> 12	158
Tumor size (cm)	≤ 3	94
	> 3	89
Breastfeeding duration (month)	≤ 6	12
	> 6	158
Primiparous age	< 30	170
	≥ 30	6
Procreative times	< 1	142
	≥ 1	33
Clinical stage	I/II	153
	III/IV	48
LN metastasis	Negative	105
	Positive	75
Family tumor history	Negative	156
	Positive	27
Incipient or recurrent	Incipient	109
	Recurrent	73
ER	Negative	60
	Positive	123
PR	Negative	75
	Positive	108
Tumor location	Left	84
	Right	97
	Both	2
Tumor type	Infiltrating ductal carcinoma	165
	Other	18
Fertility status	Negative	4
	Positive	116

LN metastasis = lymph node metastasis; ER = estrogen receptor; PR = progesterone receptor.

BMI = body mass index.

^ap value was calculated by t test.

^bp value was calculated by Pearson’s x² test.