Table 3. Incidences and hazard ratios of breast cancer based on age, mammogram screening, comorbidity, and medication characteristics in patients with or without uterine leiomyoma.

		Uterine leiomyoma
	No			Yes
Variable	Event	PY	Rate#	Event	PY	Rate#	Crude HR (95% CI)	Adjusted HR† (95% CI)
Age group
20−39	150	211147	0.71	46	54516	0.84	1.18(0.85, 1.64)	1.17(0.83, 1.63)
40−44	251	166935	1.50	82	42543	1.93	1.28(1.00, 1.64)	1.26(0.98, 1.62)
≥ 45	305	199776	1.53	115	50522	2.28	1.49(1.20, 1.85)***	1.45(1.16, 1.80)***
Mammogram screening
No	651	529987	1.23	208	122759	1.69	1.38(1.18, 1.62)***	1.34(1.14, 1.56)***
Yes	55	47871	1.15	35	24821	1.41	1.23(0.80, 1.88)	1.26(0.83, 1.94)
Comorbidity‡
No	487	430742	1.13	127	94866	1.34	1.18 (0.97, 1.44)	1.22(1.00, 1.49)*
Yes	219	147116	1.49	116	52715	2.20	1.48 (1.18, 1.85)***	1.57(1.25, 1.98)***
Medication
Estrogen
No	687	562350	1.22	229	135002	1.70	1.39(1.20, 1.61)***	1.35(1.16, 1.57)***
Yes	19	15508	1.23	14	12578	1.11	0.92(0.46, 1.84)	0.91(0.45, 1.83)
Progesterone
No	690	559916	1.23	232	136075	1.70	1.38(1.19, 1.60)***	1.32(1.13, 1.53)***
Yes	16	17942	0.89	11	11506	0.96	1.09(0.50, 2.34)	1.16(0.54, 2.50)

CI, confidence interval; HR, hazard ratio; PY, person-years;

^#Incidence rate per 1,000 person-years;

^†Multivariable analysis including age, comorbidities of hypertension, diabetes, hyperlipidemia, benign breast tumor, menopausal and postmenopausal disorders and infertility, and medication of progesterone;

^‡Patients with any comorbidity of hypertension, diabetes, hyperlipidemia, tobacco use disorders, alcohol-related diseases, benign breast tumor, menopausal and postmenopausal disorders, obesity, and infertility were classified as the comorbidity group;

*p < 0.05, ***p < 0.001.