Table 2. Incidences and hazard ratios for breast cancer and breast cancer-associated factors.

Variable	Event	PY	Rate#	Crude HR (95% CI)	Adjusted HR† (95% CI)
Uterine leiomyoma
No	706	577858	1.22	1.00	1.00
Yes	243	147581	1.65	1.35 (1.16, 1.56)***	1.31(1.13, 1.52)***
Age group
20−39	196	265662	0.74	1.00	1.00
40−44	333	209478	1.59	2.15(1.80, 2.56)***	2.11(1.77, 2.52)***
≥ 45	420	250298	1.68	2.27(1.92, 2.69)***	2.19(1.82, 2.63)***
Mammogram screening
0	824	631905	1.30	1.00	1.00
1	89	60489	1.47	1.09 (0.88, 1.36)	-
2	20	17930	1.12	0.82 (0.53, 1.28)	-
≥ 3	16	15114	1.06	0.77 (0.47, 1.26)	-
Comorbidity
Hypertension
No	826	651932	1.27	1.00	1.00
Yes	123	73507	1.67	1.32 (1.09, 1.59)**	1.05(0.85, 1.29)
Diabetes
No	916	707931	1.29	1.00	1.00
Yes	33	17507	1.88	1.48 (1.05, 2.10)*	1.26(0.87, 1.81)
Hyperlipidemia
No	854	665936	1.28	1.00	1.00
Yes	95	59503	1.60	1.25 (1.01, 1.54)*	0.93(0.74, 1.17)
TUD
No	947	724433	1.31	1.00	1.00
Yes	2	1006	1.99	1.71(0.43, 6.85)	-
ARD
No	940	720102	1.31	1.00	1.00
Yes	9	5336	1.69	1.34(0.69, 2.58)	-
BBT
No	849	693056	1.23	1.00	1.00
Yes	100	32383	3.09	2.58 (2.10, 3.18)***	2.39(1.94, 2.95)***
MPD
No	817	652027	1.25	1.00	1.00
Yes	132	73411	1.80	1.43 (1.19, 1.72)***	1.08(0.88, 1.32)
Obesity
No	938	716310	1.31	1.00	1.00
Yes	11	9128	1.21	0.96 (0.53, 1.74)	-
Infertility
No	939	708639	1.33	1.00	1.00
Yes	10	16799	0.60	0.47 (0.25, 0.88)*	0.60(0.32, 1.12)
Medication
Estrogen
No	916	697353	1.31	1.00	1.00
Yes	33	28086	1.17	0.84(0.60, 1.20)	-
Progesterone
No	922	695991	1.32	1.00	1.00
Yes	27	29448	0.92	0.66(0.45, 0.97)*	0.53(0.36, 0.77)**

ARD, alcohol-related diseases; BBT, benign breast tumor; CI, confidence interval; HR, hazard ratio; MPD, menopausal and postmenopausal disorders; PY, person-years; TUD, tobacco use disorders;

^#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;

*p < 0.05, **p < 0.01, ***p < 0.001.