Table 2. Risk of Benign Breast Diseases by the Use of Oral Contraceptives and HRT.
| Hormonal factor by age groupa | HR (95% CI)b | ||||
|---|---|---|---|---|---|
| Epithelial proliferation | Fibroadenoma | Fibrocystic changes | Cyst | ||
| With atypia | Without atypia | ||||
| Ever use of oral contraceptivesc | |||||
| Premenopausal | 1.00 (0.73-1.36) | 1.15 (0.90-1.46) | 0.83 (0.67-1.03) | 1.03 (0.89-1.19) | 1.03 (0.84-1.27) |
| Perimenopausal | 0.86 (0.64-1.16) | 1.18 (0.89-1.58) | 1.20 (0.87-1.65) | 0.98 (0.81-1.19) | 0.98 (0.83-1.16) |
| Previous use of oral contraceptivesc | |||||
| Premenopausal | 1.03 (0.74-1.42) | 1.24 (0.97-1.59) | 0.83 (0.67-1.04) | 1.08 (0.93-1.25) | 1.09 (0.88-1.35) |
| Perimenopausal | 0.87 (0.65-1.17) | 1.20 (0.90-1.60) | 1.23 (0.89-1.70) | 0.98 (0.80-1.19) | 0.99 (0.84-1.16) |
| Previous use for <8 y | |||||
| Premenopausal | 0.97 (0.66-1.41) | 1.32 (1.00-1.72)d | 0.90 (0.70-1.16) | 1.13 (0.95-1.33) | 1.17 (0.92-1.47) |
| Perimenopausal | 0.95 (0.67-1.34) | 1.37 (0.99-1.89) | 1.35 (0.94-1.93) | 1.01 (0.81-1.27) | 1.06 (0.88-1.28) |
| Previous use for ≥8 y | |||||
| Premenopausal | 1.08 (0.76-1.54) | 1.16 (0.88-1.54) | 0.75 (0.58-0.97)d | 1.04 (0.88-1.22) | 1.02 (0.80-1.29) |
| Perimenopausal | 0.82 (0.59-1.13) | 1.07 (0.79-1.47) | 1.16 (0.82-1.64) | 0.95 (0.77-1.18) | 0.94 (0.79-1.12) |
| Current use | |||||
| Premenopausal | 0.91 (0.60-1.38) | 0.93 (0.69-1.27) | 0.83 (0.63-1.09) | 0.92 (0.77-1.11) | 0.85 (0.64-1.12) |
| Perimenopausal | 0.67 (0.32-1.40) | 0.96 (0.49-1.87) | 0.59 (0.25-1.38) | 1.05 (0.70-1.58) | 0.89 (0.61-1.31) |
| Current use for <8 y | |||||
| Premenopausal | 0.71 (0.37-1.36) | 0.99 (0.65-1.52) | 1.24 (0.86-1.79) | 1.01 (0.77-1.31) | 0.93 (0.61-1.40) |
| Perimenopausal | 1.38 (0.43-4.42) | 1.53 (0.48-4.89) | 1.61 (0.50-5.17) | 0.80 (0.30-2.17) | 1.09 (0.52-2.33) |
| Current use for ≥8 y | |||||
| Premenopausal | 0.99 (0.64-1.55) | 0.91 (0.64-1.28) | 0.65 (0.47-0.90)d | 0.89 (0.73-1.09) | 0.82 (0.60-1.12) |
| Perimenopausal | 0.51 (0.20-1.27) | 0.82 (0.38-1.81) | 0.36 (0.11-1.16) | 1.11 (0.72-1.72) | 0.85 (0.55-1.30) |
| Use of HRT in postmenopausal womenc | |||||
| Ever use | 1.81 (1.07-3.07)d | 1.68 (0.93-3.04) | 1.21 (0.51-2.88) | 1.60 (1.03-2.48)d | 1.98 (1.40-2.81)d |
| Previous use | 1.46 (0.63-3.37) | 1.60 (0.64-3.98) | 0.50 (0.06-3.97) | 0.68 (0.25-1.88) | 1.47 (0.77-2.78) |
| Previous use for <5 y | 1.70 (0.54-5.35) | 1.43 (0.35-5.79) | 1.17 (0.15-9.13) | 0.78 (0.19-3.15) | 1.21 (0.44-3.32) |
| Previous use for ≥5 y | 1.30 (0.41-4.15) | 1.74 (0.54-5.61) | NAe | 0.59 (0.14-2.46) | 1.66 (0.75-3.66) |
| Current use | 2.00 (1.10-3.64)d | 1.72 (0.87-3.42) | 1.58 (0.63-4.00) | 2.02 (1.27-3.22)d | 2.20 (1.51-3.21)d |
| Current use for <5 y | 1.51 (0.54-4.19) | 1.88 (0.67-5.27) | NAe | 2.59 (1.38-4.86)d | 2.40 (1.38-4.17)d |
| Current use for ≥5 y | 2.26 (1.15-4.46)d | 1.65 (0.73-3.72) | 2.61 (1.02-6.69)d | 1.68 (0.92-3.06) | 2.09 (1.33-3.28)d |
Abbreviations: HR, hazard ratio; HRT, hormone replacement therapy; NA, not applicable.
a
Premenopausal ages are 25 to 44 years; perimenopausal ages, 45 to 54 years; and postmenopausal ages, 55 to 69 years.
b
Cox proportional hazards regression with time-varying covariates using age as the time scale adjusted for Karolinska Mammography Project for Risk Prediction of Breast Cancer unit, birth cohort, and educational level.
c
Current use includes current use and up to 4 years since last use, and previous use includes 5 years or more since last use. Never users were used as the reference group.
d
Significant association at P < .05.
e
Too few cases in this category to be analyzed in fibroadenoma.