Table 2. Distribution patterns of established breast cancer risk factors among young 890 breast cancer cases and 3,432 population-based controls.
| Factors | Control (n = 3,432)a | Luminal A (n = 455)a | Luminal B (n = 72)a | HER-2/neu (n = 117)a | Triple negative (n = 246)a |
|---|---|---|---|---|---|
| Age, mean (SD) | 45.3 (0.14) | 47.1 (0.30) | 43.8 (1.0) | 46.5 (0.7) | 44.3 (0.5) |
| Race, no. (%) | |||||
| Caucasian | 2,964 | 422 (52.1) | 65 (8.0) | 104 (12.8) | 219 (27.0) |
| African-American | 361 | 19 (39.6) | 4 (8.3) | 7 (14.6) | 18 (37.5) |
| Other | 107 | 14 (43.8) | 3 (9.4) | 6 (18.8) | 9 (28.1) |
| Age at menarche, mean (SD) | 12.7 (0.02) | 12.6 (0.1) | 12.1 (0.2) | 12.5 (0.2) | 12.5 (0.1) |
| No. of full-term births, no. (%) | |||||
| 0 | 440 | 74 (57.4) | 13 (10.1) | 13 (10.1) | 29 (22.5) |
| 1 | 362 | 53 (55.8) | 9 (9.5) | 10 (10.5) | 23 (24.2) |
| 2 | 846 | 124 (46.3) | 28 (10.5) | 30 (11.2) | 86 (32.1) |
| 3 | 758 | 88 (46.1) | 11 (5.8) | 31 (16.2) | 61 (31.9) |
| 4–14 | 1,002 | 113 (55.4) | 11 (5.4) | 33 (16.2) | 47 (23.0) |
| Age at first birth, mean (SD) | 22.5 (0.1) | 23.4 (0.2) | 23.3 (0.4) | 23.2 (0.4) | 22.6 (0.3) |
| Months of breastfeeding (among parous), mean (SD) | 5.0 (0.2) | 3.8 (0.5) | 2.0 (0.6) | 3.4 (0.6) | 2.4 (0.4) |
| Oral contraceptive use, no. (%) | |||||
| Never | 1,362 | 215 (58.1) | 25 (6.8) | 46 (12.4) | 84 (22.7) |
| Use for <3 months | 209 | 31 (59.6) | 3 (5.8) | 5 (9.6) | 13 (25.0) |
| Use for 3 or more months | 1,851 | 207 (44.6) | 44 (9.5) | 64 (13.8) | 149 (32.1) |
| Months of oral contraceptive use, mean (SD) | 32.9 (0.9) | 30.2 (2.4) | 39.0 (6.1) | 32.0 (4.6) | 39.1 (3.3) |
| Menopausal status, no. (%) | |||||
| Premenopausal | 1,282 | 198 (50.5) | 38 (9.7) | 47 (12.0) | 109 (27.8) |
| Perimenopausal | 659 | 93 (60.8) | 13 (8.5) | 12 (7.8) | 35 (22.9) |
| Postmenopausal | 1373 | 151 (48.9) | 18 (5.8) | 53 (17.2) | 87 (28.2) |
| Age at menopause, mean (SD) | 43.1 (0.2) | 45.4 (0.5) | 45.1 (1.3) | 44.7 (0.8) | 43.3 (0.7) |
| BMI among premenopausal women, no. (%) | |||||
| Underweight (<18.5 kg/m2) | 78 (6.1) | 11 (5.6) | 0 (0.0) | 3 (6.4) | 2 (1.8) |
| Normal (18.5 to <25.0 kg/m2) | 959 (75.5) | 146 (73.7) | 25 (65.8) | 38 (80.9) | 75 (68.8) |
| Overweight (25.0 to <30.0 kg/m2) | 161 (12.7) | 28 (14.1) | 9 (23.7) | 4 (8.5) | 20 (18.4) |
| Obese (30.0+ kg/m2) | 73 (5.7) | 13 (6.6) | 4 (10.5) | 2 (4.3) | 12 (11.0) |
| BMI among perimenopausal women, no. (%) | |||||
| Underweight (<18.5 kg/m2) | 20 (3.0) | 4 (4.4) | 1 (7.7) | 1 (8.3) | 0 (0.0) |
| Normal (18.5 to <25.0 kg/m2) | 443 (67.3) | 63 (69.2) | 7 (53.9) | 8 (66.7) | 23 (65.7) |
| Overweight (25.0 to <30.0 kg/m2) | 130 (19.8) | 21 (23.1) | 4 (30.8) | 2 (16.7) | 8 (22.9) |
| Obese (30.0? kg/m2) | 65 (9.9) | 3 (3.3) | 1 (7.7) | 1 (8.3) | 4 (11.4) |
| BMI among postmenopausal women, no. (%) | |||||
| Underweight (<18.5 kg/m2) | 57 (4.2) | 6 (4.0) | 1 (5.6) | 2 (3.8) | 2 (2.3) |
| Normal (18.5 to<25.0 kg/m2) | 924 (67.3) | 98 (64.9) | 10 (55.6) | 37 (69.8) | 60 (69.8) |
| Overweight (25.0 to<30.0 kg/m2) | 274 (20.0) | 36 (23.8) | 7 (38.9) | 11 (20.8) | 17 (19.8) |
| Obese (30.0+ kg/m2) | 118 (8.6) | 11 (7.3) | 0 (0.0) | 7 (8.1) | 7 (8.1) |
| Previous benign breast disease, no. (%) | |||||
| No | 3,030 | 359 (48.8) | 62 (8.4) | 104 (14.1) | 211 (28.7) |
| Yes | 401 | 92 (64.3) | 9 (6.3) | 12 (8.4) | 30 (21.0) |
| Breast cancer in first-degree relatives | |||||
| No | 3,013 | 360 (50.0) | 62 (8.6) | 104 (14.4) | 194 (26.9) |
| Yes | 218 | 54 (53.5) | 5 (5.0) | 7 (6.9) | 35 (34.7) |
a
Individual cell numbers may not sum to the total due to missing values