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Table 2. Odds ratios (ORs) and 95% confidence intervals (CIs) for breast cancer in relation to duration of use of any HRT and to duration of use of ERT and CHRT*

HRT type
 Months of use
 No. of case patients
 No. of control subjects
 OR
 Two-sided P{dagger}
No HRT 873 784 1.00 (referent)
Any HRT{ddagger} 1-60 475 406 1.07
61-120 236 186 1.21
121-180 151 140 1.14
>=181 162 121 1.36
Per 5 y 1.10 (95% CI = 1.02-1.18) .015
ERT§ 1-60 353 304 1.02
61-120 151 136 0.94
121-180 105 105 0.93
>=181 133 103 1.24
Per 5 y 1.06 (95% CI = 0.97-1.15) .18
CHRT§ 1-60 277 224 1.11
61-120 98 66 1.51
>=121 50 34 1.51
Per 5 y 1.24 (95% CI = 1.07-1.45) .005

* HRT = hormone replacement therapy; ERT = estrogen replacement therapy; and CHRT = combination hormone replacement therapy.

{dagger} P value ascertained from the difference in log-likelihood with and without variable of interest.

{ddagger} Adjusted for type of menopause and age at menopause, age at menarche, family history of breast cancer, history of benign breast disease, nulliparity, age at first full-term pregnancy, use of oral contraceptives, body weight, and alcohol use.

§ Additionally adjusted simultaneously for ERT and CHRT use.





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