Table 4. Correlation between induced abortion, OC, and IUD use and breast cancer risk.
| Premenopausal women | Postmenopausal women | |||||||
| Case N (%) |
Control N (%) |
cORe (95% CI) |
aORf (95% CI) |
Case N (%) |
Control N (%) |
cORe (95% CI) |
aORg (95% CI) |
|
| Reference groupa | 97 (22.3) | 131 (28.7) | 1.00 | 1.00 | 88 (26.7) | 105 (31.9) | 1.00 | 1.00 |
| MA,b MA+SA, or SAc ≥3 times | 36 (8.3) | 32 (7.0) | 1.52 (0.88–2.62) | 1.50 (0.84–2.66) | 25 (7.6) | 14 (4.3) | 2.13 (1.04–4.35) | 2.48 (1.14–5.40) |
| OC use only | 24 (5.5) | 26 (5.7) | 1.25 (0.68–2.30) | 1.09 (0.54–2.20) | 11 (3.3) | 10 (3.0) | 1.31 (0.53–3.24) | 1.58 (0.58–4.33) |
| ≤20 years IUD use only | 133 (29.9) | 105 (23.1) | 1.71 (1.19–2.47) | 1.71 (1.15–2.56) | 93 (28.2) | 73 (22.2) | 1.52 (1.00–2.31) | 1.72 (1.08–2.73) |
| >20 years IUD use only | 46 (10.3) | 99 (21.6) | 0.63 (0.41–0.97) | 0.41 (0.25–0.68) | 58 (17.6) | 98 (29.8) | 0.71 (0.46–1.09) | 0.85 (0.52–1.39) |
| Two or more methods usedd | 99 (22.8) | 61 (13.4) | 2.19 (1.45–3.31) | 2.35 (1.51–3.66) | 55 (16.7) | 29 (8.8) | 2.26 (1.23–3.85) | 3.49 (1.88–6.50) |
CI, confidence interval; IUD, contraceptive devices in the uterus used to practice contraception; OC, oral hormone drugs used to practice contraception.
aIncluding the subjects who had not used OC in the past 10 years, never used IUD, and either never had induced abortion or had surgical abortion ≤2.
bMedical abortion.
cSurgical abortion.
dSubjects who had used IUD for more than 20 years were excluded.
ecOR: crude OR, it is an OR value estimated by unconditional logistic regression with non-confounders adjusted.
faOR: adjusted OR, it is an OR value estimated by multivariate logistic regression with age, per capital annual income, history of active smoking, and passive smoking adjusted.
gaOR: adjusted OR, it is an OR value estimated by multivariate logistic regression with age, per capita annual income, history of active smoking, alcohol drinking, and history of live birth adjusted.