Table 1 Distribution of demographic variables and known breast cancer risk factors among women in the combined studies
From: Age of smoking initiation and risk of breast cancer in a sample of Ontario women
Risk Factor | Cases (n = 6065) | Controls (n = 6371) | |||
|---|---|---|---|---|---|
No. | % | No. | % | Chi-Square | |
Age | |||||
25 – 34 | 118 | 1.9 | 200 | 3.1 | χ2 = 43.21, df = 4, p < .001 |
35 – 44 | 807 | 13.3 | 1001 | 15.7 | |
45 – 54 | 1739 | 28.7 | 1868 | 29.3 | |
55 – 64 | 1823 | 30.1 | 1704 | 26.8 | |
65 – 75 | 1578 | 26.0 | 1598 | 25.1 | |
Age at menarche | |||||
< 12 | 1183 | 19.5 | 1155 | 18.1 | χ2 = 10.90, df = 2, p < .01 |
12 – 14 | 4200 | 69.3 | 4389 | 68.9 | |
15 + | 682 | 11.2 | 827 | 13.0 | |
Menopausal status | |||||
Pre | 1784 | 29.4 | 2133 | 33.5 | χ2 = 22.15, df = 3, p < .001 |
Post | 4192 | 69.1 | 4184 | 65.1 | |
Don't Know | 85 | 1.4 | 84 | 1.3 | |
Missing | 4 | 0.1 | 6 | 0.1 | |
Pregnancy | |||||
Never | 773 | 12.7 | 603 | 9.5 | χ2 = 33.98, df = 2, p < .001 |
Ever | 5282 | 87.1 | 5757 | 90.4 | |
Missing | 10 | 0.2 | 11 | 0.2 | |
Age at first live birth | |||||
Null parous | 773 | 12.8 | 603 | 9.5 | χ2 = 62.00, df = 5, p < .001 |
< 21 | 1141 | 18.8 | 1321 | 20.7 | |
21 – 24 | 1545 | 25.5 | 1870 | 29.4 | |
25 – 29 | 1570 | 25.9 | 1612 | 25.3 | |
30 + | 807 | 13.3 | 772 | 12.1 | |
Missing | 229 | 3.8 | 193 | 3.0 | |
Number of live births | |||||
Null parous | 773 | 12.6 | 603 | 9.5 | χ2 = 69.84, df = 4, p < .001 |
1 child | 771 | 12.7 | 755 | 11.9 | |
2 children | 2197 | 36.2 | 2255 | 35.4 | |
3 + children | 2102 | 34.7 | 2584 | 40.6 | |
Missing | 222 | 3.7 | 174 | 2.7 | |
Use of oral contraceptives | |||||
No | 2815 | 46.4 | 2825 | 44.3 | χ2 = 11.54, df = 3, p < .01 |
Yes | 3184 | 52.5 | 3466 | 54.4 | |
Don't Know | 46 | 0.8 | 40 | 0.6 | |
Missing | 20 | 0.3 | 40 | 0.6 | |
Use of hormone replacement therapy | |||||
No | 3954 | 65.2 | 4328 | 67.9 | χ2 = 15.32, df = 3, p < .01 |
Yes | 2048 | 33.8 | 1994 | 31.3 | |
Don't Know | 37 | 0.6 | 20 | 0.3 | |
Missing | 26 | 0.4 | 29 | 0.5 | |
Family history of breast cancer | |||||
No | 4692 | 77.4 | 5367 | 84.2 | χ2 = 141.53, df = 3, p < .001 |
Yes | 1130 | 18.6 | 707 | 11.1 | |
Don't Know | 65 | 1.1 | 69 | 1.1 | |
Missing | 178 | 2.9 | 228 | 3.6 | |
Benign breast disease | |||||
No | 3227 | 53.2 | 4688 | 73.6 | χ2 = 565.80, df = 3, p < .001 |
Yes | 2577 | 42.5 | 1482 | 23.3 | |
Don't know | 58 | 1.0 | 42 | 0.7 | |
Missing | 203 | 3.3 | 159 | 2.5 | |
Body mass index (kg/m2) | |||||
< 18.5 | 91 | 1.5 | 110 | 1.7 | χ2 = 8.64, df = 5, p = .124 |
18.5 – 24.9 | 2573 | 42.4 | 2836 | 44.5 | |
25 – 29.9 | 2028 | 33.4 | 2091 | 32.8 | |
30 – 34.9 | 861 | 14.2 | 832 | 13.1 | |
35+ | 435 | 7.2 | 425 | 6.7 | |
Missing | 77 | 1.3 | 77 | 1.2 | |
Family income adequacy | |||||
Low | 663 | 10.9 | 725 | 11.4 | χ2 = 6.11, df = 4, p = .191 |
Middle | 2033 | 33.5 | 2215 | 34.8 | |
High | 2183 | 36.0 | 2268 | 35.6 | |
No answer | 1007 | 16.6 | 1006 | 15.8 | |
Missing | 179 | 2.9 | 157 | 2.5 | |
Alcohol use (drinks/week) | |||||
Never drink | 1339 | 22.1 | 1358 | 21.3 | χ2 = 17.18, df = 5, p < .01 |
< 1 | 1277 | 21.1 | 1451 | 22.8 | |
1 – 3 | 1796 | 29.6 | 1980 | 31.1 | |
4 – 6 | 630 | 10.4 | 616 | 9.7 | |
7 + | 939 | 15.5 | 866 | 13.6 | |
Missing | 84 | 1.4 | 100 | 1.6 | |