Variables | Cases (n = 1353) | % | Controls (n = 1384) | % | Chi square p-value |
---|---|---|---|---|---|
Age, years (mean ± SD) | 55.0 ± 9.4 |  | 56.1 ± 9.5 |  |  |
First-degree family history of breast cancer | Â | Â | Â | Â | 0.0046 |
á…ŸNo | 1086 | 80.3 | 1158 | 83.7 | Â |
á…ŸYes | 237 | 17.5 | 187 | 13.5 | Â |
Body mass index, kg/m2 | Â | Â | Â | Â | 0.21 |
ᅟ < 25 | 779 | 57.6 | 759 | 54.8 |  |
á…Ÿ25 to 29.9 | 384 | 28.4 | 385 | 27.8 | Â |
ᅟ ≥ 30 | 160 | 11.8 | 192 | 13.9 |  |
Age at menarche, years | Â | Â | Â | Â | 0.45 |
ᅟ < 13 | 700 | 51.7 | 695 | 50.2 |  |
ᅟ ≥ 13 | 638 | 47.2 | 671 | 48.5 |  |
Parity | Â | Â | Â | Â | 0.12 |
á…Ÿ0 | 289 | 21.4 | 280 | 20.2 | Â |
á…Ÿ1 | 173 | 12.8 | 165 | 11.9 | Â |
á…Ÿ2 | 481 | 35.6 | 476 | 34.4 | Â |
á…Ÿ3 | 275 | 20.3 | 277 | 20.0 | Â |
ᅟ ≥ 4 | 120 | 8.9 | 165 | 11.9 |  |
Age at first full-term pregnancy, years | Â | Â | Â | 0.38 | |
ᅟ < 21 | 89 | 8.5 | 96 | 8.9 |  |
á…Ÿ21-24 | 325 | 31.0 | 343 | 31.7 | Â |
á…Ÿ25-29 | 415 | 39.6 | 451 | 41.6 | Â |
á…Ÿ30-34 | 169 | 16.1 | 155 | 14.3 | Â |
ᅟ ≥ 35 | 51 | 4.9 | 38 | 3.5 |  |
Hormone therapy (HT) at baseline | Â | Â | Â | Â | 0.0001 |
á…ŸPremenopausal | 364 | 26.9 | 346 | 25.0 | Â |
á…ŸPostmenopausal - never used HT | 113 | 8.4 | 150 | 10.8 | Â |
á…ŸPostmenopausal - past use HT | 76 | 5.6 | 115 | 8.3 | Â |
á…ŸPostmenopausal - current estrogen use | 200 | 14.8 | 249 | 18.0 | Â |
ᅟPostmenopausal - current estrogen + progestin use | 402 | 29.7 | 335 | 24.2 |  |
á…ŸUnknown | 198 | 14.6 | 189 | 13.7 | Â |
Strenuous or moderate physical activity, during 3Â years before baseline | Â | Â | Â | 0.0035 | |
á…Ÿ0-0.50Â hrs/week/year | 290 | 21.4 | 289 | 20.9 | Â |
á…Ÿ0.51-4.00Â hrs/week/year | 632 | 46.7 | 572 | 41.3 | Â |
á…Ÿ4.01-24Â hrs/week/year | 424 | 31.3 | 514 | 37.1 | Â |
Grams per day of alcohol, during year before baseline | Â | Â | Â | Â | 0.0006 |
á…ŸNondrinkers | 334 | 24.7 | 379 | 27.4 | Â |
ᅟ < 20 g/d | 806 | 59.6 | 836 | 60.4 |  |
ᅟ > =20 g/d | 165 | 12.2 | 109 | 7.9 |  |