Table 1 Characteristics of cases and controls, by study site
Toronto | Kingston | |||||||
|---|---|---|---|---|---|---|---|---|
Characteristic | Controls (n = 200) | Cases (n = 101) | Controls (n = 119) | Cases (n = 105) | ||||
Age, mean (SD), y | 44.9 | (9.6) | 54.3 | (11.4) | 56.1 | (11.8) | 60.6 | (11.4) |
Breast feeding, mean (SD), months | 5.7 | (10.2) | 5.3 | (9.1) | 6.5 | (15.9) | 6.5 | (9.5) |
Body mass indexa, mean (SD), kg/m2 | 23.3 | (3.9) | 24.3 | (4.3) | 25.7 | (4.5) | 25.4 | (4.7) |
Energy intakea, mean (SD), kcal/day | 957 | (385) | 991 | (307) | 981 | (385) | 1121 | (374) |
Fat intakea, mean (SD), g/day | 33.3 | (14.8) | 35.1 | (12.8) | 37.4 | (17.9) | 43.3 | (16.3) |
Smokinga, mean (SD), pack-years | 7.8 | (12.9) | 9.0 | (13.2) | 10.9 | (15.9) | 13.4 | (17.1) |
Mammographic densitya, mean (SD), % | 41.0 | (18.7) | 35.8 | (16.2) | 26.5 | (17.6) | 26.0 | (17.3) |
Menopausal status, n (%) | 54 | (27.0) | 59 | (58.4) | 79 | (66.4) | 81 | (77.1) |
Gravid, n (%) | 149 | (74.5) | 78 | (77.2) | 106 | (89.1) | 93 | (88.6) |
Age last breast fed, n (%) | ||||||||
never | 105 | (52.5) | 45 | (44.6) | 65 | (54. 6) | 46 | (43.8) |
<30 | 42 | (21.0) | 24 | (23.8) | 32 | (26.9) | 26 | (24.8) |
≥30 | 53 | (26.5) | 32 | (31.7) | 22 | (18.5) | 33 | (31.4) |
Oral contraceptives at questionnaire, n (%) | 12 | (6.0) | 8 | (7.9) | 1 | (0.8) | 1 | (1.0) |
Hormone therapy at questionnaire, n (%) | 26 | (23.0) | 8 | (7.9) | 27 | (22.7) | 10 | (9.5) |
Family history, n (%) | 83 | (41.5) | 35 | (34.7) | 41 | (34.5) | 42 | (40.0) |
Alcohol consumed >1 drink/weeka, n (%) | 103 | (52.0) | 44 | (44.0) | 52 | (43.7) | 37 | (35.6) |
Current smoking, n (%) | 49 | (24.5) | 18 | (17.8) | 25 | (21.0) | 22 | (21.0) |
Invasive cancer, n (%) | - | 88 | (87.1) | - | 94 | (89.5) | ||
Tumor steroid receptor status, n (%) | - | - | ||||||
ER+/PR+ | 55 | (54.5) | 59 | (56.2) | ||||
ER+/PR- | 10 | (9.9) | 14 | (13.3) | ||||
ER-/PR+ | 7 | (6.9) | 4 | (3.8) | ||||
ER-/PR- | 24 | (23.8) | 20 | (19.0) | ||||
Missing | 5 | (5.0) | 8 | (7.6) | ||||
Atypical hyperplasia, n (%) | 13 | (6.5) | - | 3 | (2.5) | - | ||
Nonneoplastic cells staining for ER, n (%) | ||||||||
<1% | 63 | (31.5) | 21 | (20.8) | 3 | (2.5) | 2 | (1.9) |
1–5 | 66 | (33.0) | 23 | (22.8) | 13 | (12.4) | 4 | (3.8) |
6–10 | 43 | (21.5) | 27 | (26.7) | 27 | (22.7) | 24 | (22.9) |
11–33 | 17 | (8.5) | 17 | (16.8) | 37 | (31.1) | 23 | (21.9) |
34–66 | 9 | (4.5) | 9 | (8.9) | 28 | (23.5) | 25 | (23.8) |
>66 | 2 | (1.0) | 4 | (4.0) | 11 | (9.2) | 27 | (25.7) |
Nonneoplastic cells staining for PR, n (%) | ||||||||
<1% | 20 | (10.0) | 22 | (21.8) | 16 | (13.4) | 16 | (15.2) |
1–5 | 70 | (35.0) | 27 | (26.7) | 39 | (32.8) | 36 | (34.3) |
6–10 | 62 | (31.0) | 31 | (30.7) | 47 | (39.5) | 31 | (29.5) |
11–33 | 27 | (13.5) | 12 | (11.9) | 10 | (8.4) | 12 | (11.4) |
34–66 | 12 | (6.0) | 9 | (8.9) | 7 | (5.9) | 8 | (7.6) |
>66 | 9 | (4.5) | 0 | (0.0) | 0 | (0.0) | 2 | (1.9) |