Table 2.

Association of endometrial cancer risk and timing of uterine leiomyomata diagnosis, 1995–2013

Exposure	Cases	Person- Years	Crude Rate a	IRR b	95% CI	IRR c	95% CI
History of UL
No	140	431,322	32.5	1.00	Referent	1.00	Referent
Yes	160	258,224	62.0	1.36	1.08, 1.72	1.42	1.12, 1.80
Age at UL diagnosis (years)
<30	30	62,894	47.7	1.55	1.04, 2.30	1.60	1.08, 2.39
30–39	59	116,643	50.6	1.39	1.02, 1.89	1.44	1.06, 1.97
≥40	71	78,686	90.2	1.26	0.94, 1.70	1.33	0.99, 1.80
Years since UL diagnosis
0–2	25	36,989	67.6	3.15	2.03, 4.87	3.20	2.06, 4.98
Age at UL <40	6	19,340	31.0	2.65	1.09, 6.45	2.77	1.13, 6.74
Age at UL ≥40	19	17,649	107.7	3.32	2.02, 5.46	3.35	2.03, 5.53
3–9	21	71,857	29.2	0.94	0.59, 1.49	0.95	0.60, 1.52
Age at UL <40	7	41,803	16.7	1.27	0.56, 2.85	1.29	0.57, 2.91
Age at UL ≥40	14	30,054	46.6	0.82	0.47, 1.44	0.83	0.48, 1.46
≥10	100	125,467	79.7	1.28	0.98, 1.67	1.35	1.03, 1.77
Age at UL <40	69	101,320	68.1	1.35	1.00, 1.81	1.40	1.04, 1.89
Age at UL ≥40	31	24,147	128.4	1.09	0.72, 1.64	1.18	0.79, 1.78

UL=uterine leiomyomata, IRR=incidence rate ratio, CI=confidence interval.

^aPer 100,000 person-years

^bAdjusted for age and calendar time

^cAdditionally adjusted for education, marital status, age at menarche, parity, menopausal status, oral contraceptive use, female hormones, smoking history, vigorous physical activity, and body mass index.