Table 2.

Adjusted relative risks by duration of ET use categories for 10 of the 13 studies^* included in the meta-analysis.

Author	Duration Categories**	Cases	Controls/Person Years	Adjusted RR	95% CI
Cramer (1983)34	0	145	153	1.0
	2–5	9	10	1.01	0.41 – 2.47
	6+	9	4	2.83	0.87 – 9.26
Lee (1986)30	0	134	1007	1.0
	<2	9	83	1.1	0.5 – 2.3
	2–5	8	63	1.3	0.6 – 2.8
	6+	9	57	1.7	0.8 – 3.6
Purdie (1999)28	0	663	707	1.0
	1–3	27	26	1.13	0.85 – 1.50
	4+	22	28	0.92	0.67 – 1.25
Rodriguez (2001)26	0	689	2185876	1.0
	<10	189	527202	1.11	0.94 – 1.30
	10+	66	98677	1.85	1.44 – 2.38
Lacey (2002)23	0	120	270520	1.0
	1–3	51	93804	1.3	0.96 – 1.9
	4–9	25	40451	1.6	1.0 – 2.6
	10–19	21	30058	1.8	1.1 – 3.0
	20+	16	11567	3.2	1.7 – 5.7
Riman (2002)25	0	583	3531	1.0
	1	5	34	1.07	0.40 – 2.88
	2–4	8	58	0.99	0.45 – 2.15
	5–9	11	38	1.8	0.86 – 3.75
	10+	12	36	2.14	1.03 – 4.46
Moorman (2005)17	0	129	152	1.0
	1–4	23	24	1.2	0.6 – 2.3
	5–9	17	11	1.5	0.6 – 3.5
	10+	52	32	2.2	1.2 – 4.1
Lacey (2006)14	0	87	176376	1.0
	<10	23	43458	1.15	0.72 – 1.82
	10+	26	27501	1.89	1.22 – 2.95
Beral (2007)12	0	1142	474700	1.0
	1–4	40	20300	0.89	0.64 – 1.25
	5+	196	62500	1.53	1.27 – 1.84
Rossing (2007)15	0	299	614	1.0
	1–4	25	67	0.8	0.5 – 1.4
	5–9	17	26	1.4	0.7 – 2.6
	10+	52	74	1.7	1.1 – 2.7

^*three studies^6,13,32 presented per year of use estimates and are therefore not shown in this table.

^**years of use

CI - confidence intervals

ET - estrogen-alone therapy

RR - relative risk