Table 3 Multivariate conditional logistic regression analysis for the Intervals between births, age at first birth and age at last birth as predictors of ductal breast cancer diagnosed at the ages of < 50 years and 50+ years, and lobular breast cancer diagnosed at the age of 50+ years
Variable | Ductal (< 50 years) | Ductal (50+ years) | Lobular (50+ years) | ||||||
|---|---|---|---|---|---|---|---|---|---|
N | OR | 95% CI | N | OR | 95% CI | N | OR | 95% CI | |
Intervals between births | |||||||||
1st and 2nd | |||||||||
< 1 year | 18 | 3.56 | 1.06–11.95 | 39 | 1.00 | 0.69–1.43 | 8 | 0.78 | 0.35–1.76 |
1–1.99 years | 136 | 1.00 | Ref. | 456 | 1.00 | Ref. | 102 | 1.00 | Ref. |
2–2.99 years | 62 | 0.86 | 0.44–1.70 | 138 | 0.83 | 0.67–1.03 | 33 | 1.01 | 0.64–1.60 |
3+ years | 36 | 0.38 | 0.14–1.00 | 152 | 1.23 | 0.98–1.54 | 32 | 1.45 | 0.88–2.42 |
p-trend | < 0.001 | 0.47 | 0.18 | ||||||
2nd and 3rd | |||||||||
< 1 year | 9 | 0.43 | 0.07–2.50 | 42 | 1.06 | 0.74–1.52 | 6 | 0.70 | 0.28–1.75 |
1–1.99 years | 123 | 1.00 | Ref. | 363 | 1.00 | Ref. | 68 | 1.00 | Ref. |
2–2.99 years | 48 | 0.39 | 0.18–0.83 | 162 | 0.90 | 0.73–1.11 | 45 | 1.46 | 0.94–2.28 |
3+ years | 72 | 0.50 | 0.23–1.11 | 218 | 0.98 | 0.79–1.20 | 56 | 1.34 | 0.84–2.13 |
p-trend | 0.91 | 0.55 | 0.11 | ||||||
3rd and 4th | |||||||||
< 1 year | 11 | 6.76 | 1.52–30.11 | 25 | 0.80 | 0.51–1.25 | 9 | 2.07 | 0.89–4.79 |
1–1.99 years | 83 | 1.00 | Ref. | 303 | 1.00 | Ref. | 52 | 1.00 | Ref. |
2–2.99 years | 60 | 1.32 | 0.60–2.90 | 183 | 1.04 | 0.84–1.28 | 38 | 1.35 | 0.82–2.22 |
3+ years | 98 | 1.36 | 0.65–2.88 | 274 | 0.90 | 0.74–1.11 | 76 | 1.64 | 1.01–2.65 |
p-trend | 0.07 | 0.55 | 0.75 | ||||||
4th and 5th | |||||||||
< 1 year | 10 | 0.54 | 0.10–3.00 | 42 | 1.19 | 0.81–1.74 | 8 | 0.97 | 0.28–1.59 |
1–1.99 years | 72 | 1.00 | Ref. | 218 | 1.00 | Ref. | 43 | 1.00 | Ref. |
2–2.99 years | 60 | 1.13 | 0.54–2.35 | 167 | 1.07 | 0.85–1.33 | 39 | 1.43 | 0.85–2.38 |
3+ years | 110 | 0.88 | 0.41–1.89 | 358 | 1.00 | 0.80–1.23 | 85 | 1.43 | 0.87–2.35 |
p-trend | 0.45 | 0.43 | 0.26 | ||||||
Age at first birth | |||||||||
< 20 years | 66 | 1.00 | Ref. | 275 | 1.00 | Ref | 48 | 1.00 | Ref. |
20–24 years | 105 | 1.02 | 0.49–2.14 | 339 | 0.89 | 0.74–1.08 | 72 | 1.00 | 0.65–1.53 |
25–29 years | 64 | 1.36 | 0.55–3.31 | 143 | 1.16 | 0.88–1.51 | 39 | 1.82 | 1.02–3.29 |
30+ years | 17 | 2.65 | 0.57–12.22 | 28 | 1.19 | 0.72–1.95 | 16 | 5.35 | 2.12–13.47 |
p-trend | 0.12 | 0.33 | < 0.001 | ||||||
Age at last birth | |||||||||
< 30 years | 15 | 1.00 | Ref. | 140 | 1.00 | Ref. | 17 | 1.00 | Ref. |
30–34 years | 50 | 2.30 | 0.63–8.40 | 192 | 1.17 | 0.89–1.53 | 43 | 1.98 | 1.02–3.88 |
35–39 years | 90 | 4.13 | 1.02–16.59 | 181 | 1.06 | 0.77–1.46 | 41 | 1.44 | 0.66–3.16 |
40+ years | 97 | 5.63 | 1.41–22.55 | 272 | 1.17 | 0.83–1.65 | 74 | 1.89 | 0.81–4.44 |
p-trend | 0.03 | 0.51 | 0.25 | ||||||