Table 3.

Odds Ratios and 95% Confidence Intervals for Invasive Breast Cancer According to Benign Gynecologic Conditions, Age at Diagnosis, and Gynecologic Surgery Status of US Women, 1992–1995

Characteristic	Full Study Population				Bilateral Oophorectomy With Hysterectomya				Intact Uterus and Ovariesa
	Cases (n = 4,935)	Controls (n = 5,111)	ORb	95% CI	Cases (n = 885)	Controls (n = 961)	ORb	95% CI	Cases (n = 3,181)	Controls (n = 3,271)	ORb	95% CI
Uterine fibroids
No	3,964	4,170	1		495	601	1		2,868	2,999	1
Yes	845	835	1.13	1.01, 1.26	378	353	1.32	1.08, 1.61	254	244	1.14	0.94, 1.37
Diagnosed at age <35 years	158	170	1.14	0.91, 1.44	46	66	0.97	0.64, 1.47	61	56	1.26	0.86, 1.83
Diagnosed at ages 35–44 years	311	314	1.16	0.98, 1.38	129	121	1.44	1.07, 1.93	79	67	1.19	0.85, 1.67
Diagnosed at age ≥45 years	349	331	1.08	0.91, 1.27	198	161	1.39	1.06, 1.81	97	109	1.00	0.75, 1.33
P-trend			0.08				0.002				0.5
Endometriosis
No	4,642	4,789	1		782	810	1		3,088	3,212	1
Yes	198	228	0.99	0.80, 1.21	95	142	0.82	0.60, 1.10	54	44	1.23	0.81, 1.85
Diagnosed at age <35 years	81	85	1.14	0.83, 1.57	30	53	0.76	0.46, 1.23	26	15	1.83	0.95, 3.51
Diagnosed at ages 35–44 years	66	78	1.00	0.71, 1.41	37	45	1.07	0.66, 1.74	16	16	0.97	0.48, 1.98
Diagnosed at age ≥45 years	48	59	0.83	0.56, 1.22	27	41	0.69	0.41, 1.15	11	11	0.98	0.42, 2.29
P-trend			0.5				0.2				0.6

Abbreviations: CI, confidence interval; OR, odds ratio.

^aThe total numbers of cases and controls with bilateral oophorectomy with hysterectomy and intact uterus and ovaries do not equal the full study population because women with removal of the uterus alone, uterus plus 1 ovary, 1 ovary alone, or 2 ovaries alone were excluded.

^bOdds ratios were adjusted for age, US state, age at menarche, duration of oral contraceptive use, parity, age at first birth, age at menopause, postmenopausal hormone use, body mass index, mammography screening, and family history of breast cancer.