. 2018 Mar 30;170(3):487–497. doi: 10.1007/s10549-018-4768-0

Table 4.

Linear regression analysis of epithelial ER and risk factors, for all women and stratified by menopausal status, adjusted for age and BMI

Variables	Epithelial ER (%)^a			Epithelial ER (%)^a			Epithelial ER (%)^a
	All women (N = 153)			Premenopausal women (N = 55)			Postmenopausal women (N = 95)
	N	Estimates β (SE)	p	N	Estimates β (SE)	p	N	Estimates β (SE)	p
Age at biopsy (y)	110	0.010 (0.005)	0.033^b	37	0.006 (0.016)	0.734^b	71	0.012 (0.009)	0.180^b
BMI (Kg/m²)	108	0.025 (0.014)	0.082^c	36	0.015 (0.020)	0.445^c	70	0.041 (0.022)	0.064^c
Age at menarche (y)	103	− 0.042 (0.030)	0.167	35	− 0.030 (0.053)	0.581	68	− 0.851 (0.989)	0.392
Age at first birth (y)	94	− 0.018 (0.009)	0.051	32	− 0.030 (0.013)	0.025	62	− 0.006 (0.013)	0.649
Age at menopause (y)			N.A.			N.A.	61	− 0.015 (0.012)	0.221
Parous status^d	105	0.250 (0.142)	0.081	36	0.079 (0.247)	0.750	69	0.408 (0.179)	0.026
Pregnancies (number)	105	0.053 (0.027)	0.051	36	0.018 (0.045)	0.698	69	0.074 (0.034)	0.035
Births (number)	105	0.100 (0.041)	0.017	36	0.044 (0.070)	0.535	69	0.132 (0.052)	0.013
Pregnancies without birth (number)	105	0.030 (0.045)	0.503	36	− 0.001 (0.072)	0.985	69	0.049 (0.059)	0.413
Breastfeeding (months)^e	88	0.007 (0.004)	0.120	29	− 0.002 (0.007)	0.785	59	0.011 (0.005)	0.040
Ever taken oral contraceptives^f	103	0.104 (0.121)	0.394	36	0.125 (0.337)	0.714	67	0.093 (0.133)	0.489
Postmenopausal status^g	106	0.024 (0.146)	0.868			N.A.			N.A.
Ever taken hormone replacement therapy^f	105	− 0.009 (0.109)	0.933	36		N.D.	69	0.060 (0.117)	0.609
Benign breast disorder^f	107	0.022 (0.098)	0.824	35	0.094 (0.204)	0.650	70	− 0.004 (0.119)	0.971

BMI body mass index, ER oestrogen receptor, N.A. not applicable, N.D. not determined, SE standard error, y years

^aLog transformed variable

^bUnadjusted model

^cAdjusted for age

^dParous versus nulliparous

^eMinimum total duration of breastfeeding (months) among parous women

^fEver versus never

^gPostmenopausal versus premenopausal