Table 3.

Breast Cancer Incidence Model for 1988–2000 Among Women in the Nurses’ Health Study, Unweighted and Weighted by Inverse Probability of Screening

Variable	Unweighted		Weighted
	β (SE)	P Value	β (SE)	P Value
Constant	−9.597 (0.362)	<0.0001	−9.379 (0.367)	<0.0001
Premenopause duration, yearsa	0.088 (0.009)	<0.0001	0.085 (0.009)	<0.0001
Menopause duration, years
Natural	0.034 (0.006)	<0.0001	0.034 (0.006)	<0.0001
Bilateral oophorectomy	0.025 (0.007)	0.0006	0.027 (0.007)	0.0003
Pregnancy history
Age at first birth − age at menarche	0.0067 (0.0050)	0.18	0.0048 (0.0052)	0.36
Birth indexb	−0.0030 (0.0007)	<0.0001	−0.0036 (0.0007)	<0.0001
Benign breast disease
BBD, yes versus no	0.638 (0.601)	0.29	0.203 (0.628)	0.75
BBD × age at menarche	0.051 (0.024)	0.037	0.064 (0.026)	0.014
BBD × premenopause duration	−0.019 (0.012)	0.10	−0.014 (0.012)	0.24
BBD × menopause duration	−0.015 (0.006)	0.016	−0.015 (0.007)	0.027
Hormone therapy
Oral estrogen duration	0.029 (0.008)	0.0002	0.027 (0.008)	0.0016
Oral estrogen and progesterone duration	0.062 (0.011)	<0.0001	0.062 (0.012)	<0.0001
Other hormone types’ duration	0.036 (0.011)	0.0007	0.028 (0.011)	0.01
Current use	0.073 (0.072)	0.31	−0.104 (0.077)	0.17
Past use	−0.095 (0.074)	0.20	−0.151 (0.076)	0.05
Body mass index, kg/m2
Average BMI during premenopause × premenopause durationc	−0.00089 (0.00024)	0.0002	−0.00087 (0.00025)	0.0006
Average BMI during postmenopause × menopause durationd	0.0034 (0.0006)	<0.0001	0.0034 (0.0006)	<0.0001
Height, inches
Height × premenopause durationc	0.00098 (0.00031)	0.0015	0.00100 (0.00033)	0.002
Height × menopause durationd	−0.00044 (0.00130)	0.74	−0.00039 (0.00133)	0.77
Alcohol use
Cumulative ounces before menopause	0.00038 (0.00009)	<0.0001	0.00040 (0.00009)	<0.0001
Cumulative ounces after menopause
With hormone therapy	−0.00087 (0.0004)	0.030	−0.00071 (0.00041)	0.08
Without hormone therapy	−0.00022 (0.00030)	0.47	−0.00018 (0.00030)	0.55
Family history of breast cancer	0.403 (0.061)	<0.0001	0.339 (0.064)	<0.0001

Abbreviations: BBD, benign breast disease; BMI, body mass index; SE, standard error.

^aPremenopause duration = minimum(age, age at menopause) − age at menarche.

^bBirth index = sum of (minimum(age, age at menopause) − age at ith birth) over all births for parous women; birth index = 0 for nulliparous women.

^cIncluding time postmenopausal while taking postmenopausal hormones.

^dTime postmenopausal while not taking postmenopausal hormones.