Table 2.

The association between endometriosis and average mammographic density measurements (linear regression estimates) in the Nurses’ Health Study II

		Model 1	Model 2	Model 3a
	Mean +/− SD	Difference (95% CI)
Premenopausal Women (n=1,241) (No endometriosis n=1,150, Endometriosis n=91)
Average Percent Mammographic Density
No Endometriosis	40.54 +/− 17.87	0 (ref)	0 (ref)	0 (ref)
Endometriosis	43.07 +/− 17.54	1.77 (−1.71, 5.24)	2.03 (−1.28, 5.34)	2.00 (−1.33, 5.33)
Average Dense Area (cm2)
No Endometriosis	94.86 +/− 52.52	0 (ref)	0 (ref)	0 (ref)
Endometriosis	96.61 +/−49.58	1.17 (−9.49, 11.83)	1.32 (−8.82, 11.47)	0.10 (−9.74, 9.94)
Average Non-Dense Area (cm2)
No Endometriosis	147.52 +/−76.15	0 (ref)	0 (ref)	0 (ref)
Endometriosis	137.75 +/− 75.95	−5.70 (−19.00, 7.61)	−8.80 (−22.39, 4.80)	−8.45 (−22.34, 5.44)
Postmenopausal Women(n=340) (No endometriosis n=263, Endometriosis n=77)
Average Percent Mammographic Density
No Endometriosis	32.24 +/− 17.47	0 (ref)	0 (ref)	0 (ref)
Endometriosis	32.33 +/− 16.26	−1.38 (−5.02,2.26)	−2.04 (−5.74,1.67)	−0.89 (−5.10,3.33)
Average Dense Area (cm2)
No Endometriosis	75.12 +/− 48.91	0 (ref)	0 (ref)	0 (ref)
Endometriosis	73.86 +/−39.77	−4.02 (−14.84,6.80)	−3.60 (−14.27,7.07)	−2.71(−15.34,9.93)
Average Non-Dense Area (cm2)
No Endometriosis	167.97+/−84.81	0 (ref)	0 (ref)	0 (ref)
Endometriosis	167.34 +/− 79.31	4.28 (−12.93, 21.50)	4.41 (−13.88, 22.70)	3.38 (−15.82, 22.57)

Model 1 Adjusted for age and BMI at mammogram

Model 2 Additionally adjusted for alcohol consumption, family history of breast cancer, smoking history, history of benign breast disease, bmi at age 18, parity, age at menarche, oral contraceptive use history, and breastfeeding history

Model 3 a:Pre-menopausal additionally adjusted for hysterectomy, hormone theraphy

^aPost-menopausal additionally adjusted for hysterectomy, oophorectomy, and hormone therapy