Table 3.
Multivariable adjusted* odds ratio (OR) and 95% confidence interval (CI) for triple negative and luminal A breast cancer associated with oral contraceptives use by age
| Younger (age 35–44 years) | Older (age 45–64 years) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| No. controls |
No. triple negative |
No. luminal A |
OR (95% CI) of triple negative |
OR (95% CI) of luminal A |
No. controls |
No. triple negative |
No. luminal A |
OR (95% CI) of triple negative |
OR (95% CI) of luminal A |
|
| Oral contraceptive use | ||||||||||
| Never use | 74 | 21 | 22 | Reference | Reference | 336 | 38 | 133 | Reference | Reference |
| Ever use | 647 | 133 | 175 | 0.72 (0.42–1.24) | 0.97 (0.57–1.64) | 958 | 143 | 315 | 1.25 (0.83–1.88) | 0.92 (0.71–1.20) |
| Test for homogeneity P-value | 0.38 | 0.18 | ||||||||
| Duration of use, years | ||||||||||
| <1 | 135 | 18 | 33 | 0.44 (0.22–0.90) | 0.91 (0.48–1.72) | 223 | 39 | 83 | 1.49 (0.91–2.45) | 1.03 (0.73–1.45) |
| 1–4 | 222 | 42 | 72 | 0.66 (0.36–1.22) | 1.20 (0.68–2.11) | 318 | 44 | 107 | 1.15 (0.70–1.89) | 0.98 (0.70–1.35) |
| 5–9 | 158 | 39 | 35 | 0.87 (0.46–1.62) | 0.78 (0.42–1.45) | 238 | 36 | 66 | 1.26 (0.75–2.12) | 0.78 (0.54–1.12) |
| ≥10 | 132 | 34 | 35 | 0.92 (0.49–1.73) | 0.90 (0.49–1.68) | 179 | 24 | 59 | 1.06 (0.60–1.88) | 0.85 (0.58–1.24) |
| Trend p-value | 0.25 | 0.54 | 0.95 | 0.18 | ||||||
| Test for homogeneity of trends P-value | 0.16 | 0.36 | ||||||||
| Age at first use, years | ||||||||||
| ≥25 | 52 | 8 | 17 | 0.55 (0.22–1.38) | 1.26 (0.60–2.66) | 347 | 46 | 119 | 1.23 (0.77–1.95) | 0.88 (0.65–1.18) |
| 20–24 | 164 | 35 | 50 | 0.74 (0.39–1.40) | 1.11 (0.61–2.01) | 405 | 54 | 144 | 1.11 (0.68–1.83) | 1.03 (0.74–1.42) |
| 18–19 | 183 | 40 | 49 | 0.78 (0.42–1.44) | 0.94 (0.52–1.70) | 149 | 22 | 31 | 1.17 (0.62–2.20) | 0.65 (0.40–1.06) |
| <18 | 248 | 50 | 59 | 0.70 (0.38–1.27) | 0.82 (0.46–1.47) | 57 | 21 | 21 | 2.87 (1.44–5.74) | 1.36 (0.75–2.48) |
| Trend p-value | 0.46 | 0.23 | 0.04 | 0.85 | ||||||
| Test for homogeneity of trends P-value | 0.11 | 0.05 | ||||||||
| Duration between menarche and first use, years | ||||||||||
| <5 | 200 | 44 | 46 | 0.75 (0.40–1.40) | 0.82 (0.44–1.50) | 64 | 14 | 16 | 1.59 (0.75–3.39) | 0.79 (0.42–1.51) |
| 5–9 | 329 | 64 | 95 | 0.69 (0.38–1.23) | 1.02 (0.59–1.77) | 333 | 55 | 93 | 1.28 (0.77–2.14) | 0.80 (0.56–1.15) |
| 10–14 | 93 | 20 | 25 | 0.76 (0.38–1.56) | 0.98 (0.50–1.92) | 344 | 44 | 127 | 1.16 (0.71–1.88) | 1.02 (0.75–1.40) |
| ≥15 | 25 | 5 | 9 | 0.71 (0.24–2.16) | 1.41 (0.56–3.54) | 217 | 30 | 79 | 1.28 (0.76–2.14) | 0.90 (0.64–1.26) |
| Trend p-value | 0.42 | 0.45 | 0.48 | 0.81 | ||||||
| Test for homogeneity of trends P-value | 0.22 | 0.43 | ||||||||
| Time since last use, years | ||||||||||
| <5 | 130 | 26 | 38 | 0.68 (0.35–1.32) | 0.97 (0.52–1.81) | 35 | 3 | 6 | 0.69 (0.19–2.45) | 0.39 (0.15–0.98) |
| 5–9 | 89 | 23 | 34 | 0.88 (0.44–1.76) | 1.35 (0.71–2.55) | 27 | 4 | 5 | 1.13 (0.36–3.58) | 0.50 (0.18–1.38) |
| 10–14 | 153 | 33 | 35 | 0.76 (0.40–1.45) | 0.82 (0.44–1.52) | 66 | 12 | 33 | 1.42 (0.67–2.98) | 1.35 (0.82–2.22) |
| 15–19 | 155 | 31 | 33 | 0.70 (0.37–1.34) | 0.78 (0.41–1.46) | 172 | 20 | 53 | 0.96 (0.52–1.76) | 0.87 (0.58–1.29) |
| ≥20 | 120 | 20 | 35 | 0.59 (0.29–1.21) | 1.10 (0.58–2.08) | 658 | 104 | 218 | 1.31 (0.87–2.00) | 0.93 (0.70–1.22) |
| Trend p-value | 0.26 | 0.64 | 0.17 | 0.90 | ||||||
| Test for homogeneity of trends P-value | 0.56 | 0.19 | ||||||||
Note: Triple negative = ER−/PR−/HER2−, Luminal A = ER+ or PR+ plus HER2−.
*
Adjusted for study site, race, education, age, family history of breast cancer, age at menarche, menopausal status, body mass index, parity.