Table 3.
The association between reproductive factors and invasive breast cancer risk by the source of data on ER and PR status among women ages 35 to 64 y in the Women's CARE Study
| No. of controls | No. of cases | Multivariable adjusted* odds ratio (95% CI) | |||||||
|---|---|---|---|---|---|---|---|---|---|
|
|
|||||||||
| ER−/PR− | ER+/PR+ | ER+/PR− | ER−/PR+ | ER−/PR− | ER+/PR+ | ER+/PR− | ER−/PR+ | ||
| Number of full-term pregnancies * | |||||||||
| ER/PR measured in a centralized pathology laboratory | |||||||||
| Never pregnant | 178 | 26 | 59 | 10 | 8 | Reference | Reference | Reference | Reference |
| 1 | 315 | 64 | 78 | 16 | 11 | 1.25 (0.76–2.07) | 0.85 (0.57–1.27) | 0.87 (0.38–2.01) | 0.77 (0.30–1.99) |
| 2 | 576 | 112 | 120 | 19 | 22 | 1.28 (0.80–2.04) | 0.69 (0.48–1.00) | 0.58 (0.26–1.30) | 0.87 (0.37–2.03) |
| 3 | 396 | 57 | 80 | 12 | 6 | 1.00 (0.60–1.67) | 0.69 (0.47–1.03) | 0.53 (0.22–1.28) | 0.35 (0.12–1.05) |
| ≥4 | 405 | 58 | 71 | 13 | 7 | 0.99 (0.59–1.68) | 0.60 (0.39–0.92) | 0.55 (0.22–1.34) | 0.44 (0.15–1.31) |
| P trend | 0.38 | 0.008 | 0.09 | 0.05 | |||||
| Pregnant but no full-term pregnancy | 159 | 25 | 38 | 4 | 3 | 0.92 (0.50–1.67) | 0.74 (0.46–1.19) | 0.44 (0.13–1.44) | 0.38 (0.10–1.46) |
| ER/PR from SEER registries | |||||||||
| Never pregnant | 178 | 19 | 68 | 8 | 8 | Reference | Reference | Reference | Reference |
| 1 | 315 | 46 | 92 | 15 | 16 | 1.20 (0.68–2.13) | 0.85 (0.58–1.24) | 1.15 (0.47–2.81) | 1.07 (0.44–2.61) |
| 2 | 576 | 82 | 149 | 30 | 12 | 1.23 (0.72–2.10) | 0.75 (0.53–1.05) | 1.23 (0.54–2.76) | 0.47 (0.19–1.19) |
| 3 | 396 | 56 | 85 | 9 | 5 | 1.29 (0.74–2.28) | 0.64 (0.44–0.94) | 0.49 (0.18–1.32) | 0.31 (0.10–0.99) |
| ≥4 | 405 | 47 | 76 | 18 | 8 | 1.04 (0.57–1.87) | 0.57 (0.38–0.85) | 0.89 (0.36–2.20) | 0.53 (0.18–1.54) |
| P trend | 0.98 | 0.002 | 0.20 | 0.02 | |||||
| Pregnant but no full-term pregnancy | 159 | 16 | 43 | 8 | 3 | 0.77 (0.38–1.57) | 0.71 (0.45–1.11) | 1.30 (0.47–3.61) | 0.38 (0.10–1.47) |
| ER/PR status consistently ascertained by both sources | |||||||||
| Never pregnant | 178 | 16 | 54 | – | – | Reference | Reference | – | – |
| 1 | 315 | 38 | 69 | – | – | 1.19 (0.64–2.23) | 0.83 (0.55–1.26) | – | – |
| 2 | 576 | 78 | 106 | – | – | 1.40 (0.79–2.49) | 0.69 (0.47–1.01) | – | – |
| 3 | 396 | 48 | 69 | – | – | 1.33 (0.72–2.44) | 0.67 (0.45–1.02) | – | – |
| ≥4 | 405 | 44 | 62 | – | – | 1.15 (0.61–2.17) | 0.59 (0.38–0.92) | – | – |
| P trend | 0.75 | 0.01 | – | – | |||||
| Pregnant but no full-term pregnancy | 159 | 16 | 32 | 0.94 (0.45–1.96) | 0.67 (0.41–1.11) | – | – | ||
| Age at first full-term pregnancy,†y | |||||||||
| ER/PR measured in a centralized laboratory | |||||||||
| ≤19 | 586 | 96 | 87 | 22 | 10 | Reference | Reference | Reference | Reference |
| 20–24 | 618 | 101 | 134 | 17 | 16 | 1.06 (0.77–1.46) | 1.38 (1.01–1.89) | 0.60 (0.31–1.19) | 1.47 (0.64–3.38) |
| 25–29 | 282 | 53 | 825 | 15 | 15 | 1.19 (0.79–1.80) | 1.90 (1.29–2.78) | 1.15 (0.53–2.51) | 2.80 (1.12–7.02) |
| ≥30 | 206 | 41 | 43 | 6 | 5 | 1.25 (0.76–2.05) | 1.26 (0.77–2.06) | 0.58 (0.20–1.72) | 1.14 (0.32–4.03) |
| P trend | 0.31 | 0.05 | 0.63 | 0.29 | |||||
| ER/PR from SEER registries | |||||||||
| ≤19 | 586 | 81 | 99 | 24 | 11 | Reference | Reference | Reference | Reference |
| 20–24 | 618 | 80 | 155 | 21 | 12 | 1.01 (0.71–1.43) | 1.39 (1.03–1.87) | 0.71 (0.37–1.35) | 0.98 (0.41–2.35) |
| 25–29 | 282 | 45 | 99 | 16 | 8 | 1.26 (0.81–1.97) | 1.82 (1.27–2.61) | 1.28 (0.60–2.72) | 1.38 (0.49–3.92) |
| ≥30 | 206 | 25 | 49 | 11 | 10 | 1.02 (0.57–1.82) | 1.14 (0.72–1.81) | 1.37 (0.56–3.37) | 1.94 (0.63–5.93) |
| P trend | 0.61 | 0.11 | 0.35 | 0.20 | |||||
| ER/PR status consistently ascertained by both sources | |||||||||
| ≤19 | 586 | 74 | 77 | – | – | Reference | Reference | – | – |
| 20–24 | 618 | 73 | 122 | – | – | 1.04 (0.72–1.51) | 1.47 (1.06–2.05) | – | – |
| 25–29 | 282 | 38 | 73 | – | – | 1.22 (0.76–1.96) | 1.83 (1.22–2.75) | – | – |
| ≥30 | 206 | 23 | 34 | – | – | 1.10 (0.60–2.00) | 1.09 (0.64–1.85) | – | – |
| P trend | 0.57 | 0.18 | – | – | |||||
| Duration of breastfeeding,†mo | |||||||||
| ER/PR measured in a centralized laboratory | |||||||||
| Never | 715 | 135 | 152 | 32 | 25 | Reference | Reference | Reference | Reference |
| <1 | 203 | 37 | 52 | 9 | 3 | 0.99 (0.66–1.48) | 1.11 (0.77–1.60) | 0.98 (0.45–2.13) | 0.37 (0.11–1.28) |
| 1–6 | 336 | 55 | 65 | 9 | 1.0 | 0.79 (0.55–1.13) | 0.75 (0.54–1.06) | 0.51 (0.23–1.12) | 0.58 (0.26–1.28) |
| 7–23 | 304 | 44 | 62 | 8 | 6 | 0.70 (0.47–1.03) | 0.79 (0.55–1.12) | 0.52 (0.23–1.20) | 0.40 (0.15–1.05) |
| ≥24 | 134 | 20 | 18 | 2 | 2 | 0.77 (0.45–1.32) | 0.55 (0.31–0.96) | 0.32 (0.07–1.43) | 0.31 (0.07–1.47) |
| P trend | 0.05 | 0.02 | 0.02 | 0.03 | |||||
| ER/PR from SEER registries | |||||||||
| Never | 715 | 111 | 173 | 39 | 21 | Reference | Reference | Reference | |
| <1 | 203 | 29 | 60 | 7 | 5 | 0.93 (0.59–1.45) | 1.16 (0.82–1.64) | 0.60 (0.26–1.38) | 0.76 (0.28–2.10) |
| 1–6 | 336 | 40 | 79 | 13 | 7 | 0.70 (0.47–1.06) | 0.80 (0.58–1.10) | 0.61 (0.31–1.19) | 0.55 (0.22–1.37) |
| 7–23 | 304 | 34 | 70 | 9 | 7 | 0.64 (0.41–0.98) | 0.78 (0.56–1.10) | 0.50 (0.23–1.08) | 0.65 (0.26–1.67) |
| ≥24 | 134 | 17 | 20 | 4 | 1 | 0.74 (0.41–1.34) | 0.55 (0.32–0.93) | 0.56 (0.19–1.68) | 0.24 (0.03–1.89) |
| P trend | 0.03 | 0.01 | 0.05 | 0.10 | |||||
| ER/PR status consistently ascertained by both sources | |||||||||
| Never | 715 | 96 | 130 | – | – | Reference | Reference | – | – |
| <1 | 203 | 29 | 46 | – | – | 1.08 (0.68–1.70) | 1.15 (0.78–1.70) | – | – |
| 1–6 | 336 | 37 | 60 | – | – | 0.79 (0.52–1.20) | 0.84 (0.59–1.19) | – | – |
| 7–23 | 304 | 31 | 54 | – | – | 0.69 (0.44–1.09) | 0.83 (0.57–1.20) | – | – |
| ≥24 | 134 | 15 | 16 | – | – | 0.77 (0.41–1.42) | 0.58 (0.32–1.05) | – | – |
| P trend | 0.09 | 0.06 | – | – | |||||
*
Adjusted for categorical variables of age, race, family history of breast cancer, age at menarche, education and study site.
†
Additionally adjusted for number of full-term-pregnancies and mutually adjusted for age at first full-term pregnancy and duration of breastfeeding.