Breast cancer risk associated with different HRT formulations: a register-based case-control study

BMC Women's Health

Table 3 Risk of breast cancer associated with HRT: Ever- use vs. never use of HRT.

	e-case¹	e-ctrl.¹	Crude OR (95% CI)	Adj. OR (95% CI)
Ever HRT	1492	3142	1.1 (0.99–1.2)	1.2 (1.0–1.3)
Duration of use ²
<2 yrs	387	770	1.3 (1.1–1.5)	1.3 (1.1–1.6)
2–4 yrs	223	670	0.8 (0.7–0.9)	0.9 (0.7–1.1)
5–7 yrs	278	609	1.0 (0.9–1.2)	1.1 (0.9–1.3)
8+ yrs	604	1093	1.2 (1.0–1.4)	1.2 (1.1–1.4)
Time since first use ²			P trend = .08	P trend = .06
1–4 yrs	514	1187	1.1 (0.97–1.3)	1.2 (1.1–1.4)
5–9 yrs	556	1098	1.1 (0.98–1.3)	1.2 (1.0–1.4)
10–14 yrs	294	599	1.0 (0.9–1.2)	0.97 (0.8–1.2)
15+ yrs	128	258	1.1 (0.9–1.4)	0.96 (0.7–1.3)
Time since last use ²			P trend = .19	P trend = .51
-1 yr/current use	1381	2908	1.1 (0.99–1.2)	1.2 (1.0–1.3)
1–2 yrs	71	162	0.96 (0.7–1.3)	0.9 (0.6–1.3)
3–4 yrs	31	63	1.0 (0.6–1.6)	1.1 (0.6–1.9)
5+ yrs	9	9	1.7 (0.6–4.3)	2.3 (0.7–7.2)
			P trend = .14	P trend = .054

Conditional logistic regression analysis [Odds ratios (OR) and 95% confidence intervals]; adjustment for BMI, family history of breast cancer, childbearing history, age at first live birth, duration of breast-feeding, age at menarche, ever OC use, education. Index dates 0.5 = exposure information was not considered 0.5 year prior to cancer diagnosis.
¹ e-case, e-ctrl = number of observations for exposed case or exposed control respectively.
² time variables were rounded

ISSN: 1472-6874