Descriptive statistics of subjects stratified by case or control status (total observations with percentage in parentheses)
| Variable | Cases (n = 428) | Controls (n = 426) | Total (n = 854) | Pa |
|---|---|---|---|---|
| Age at entry (yrs) | ||||
| <50 | 58 (13.5) | 86 (20.2) | 144 (16.9) | |
| 50–54 | 61 (14.3) | 76 (20.2) | 137 (16.0) | |
| 55–59 | 65 (15.2) | 65 (15.3) | 130 (15.2) | |
| 60–64 | 79 (18.5) | 59 (13.9) | 138 (16.2) | |
| 65–69 | 90 (21.0) | 83 (19.5) | 173 (20.3) | |
| 70–74 | 69 (16.1) | 51 (12.0) | 120 (14.1) | |
| ≥75 | 6 (1.4) | 6 (1.4) | 12 (1.4) | 0.05 |
| Ethnicity | ||||
| African American | 117 (27.3) | 117 (27.5) | 234 (27.4) | |
| Japanese | 100 (23.4) | 100 (23.5) | 200 (23.4) | |
| Latina | 101 (23.6) | 99 (23.2) | 200 (23.4) | |
| White | 110 (25.7) | 110 (25.8) | 220 (25.8) | 0.9995 |
| Family history of breast cancer | ||||
| Reported | 77 (18.0) | 42 (9.9) | 119 (13.9) | 0.0090 |
| Any <50 yrs | 33 (7.7) | 17 (4.0) | 50 (5.9) | 0.0015 |
| Family history of ovarian cancer | 19 (4.4) | 21 (4.9) | 40 (4.7) | 0.8594 |
| Age at first menstrual period (yrs) | ||||
| <13 | 229 (54.1) | 211 (49.9) | 440 (52.0) | |
| 13 | 194 (45.9) | 212 (50.1) | 406 (48.0) | 0.2420 |
| No. of children | ||||
| None | 29 (7.8) | 25 (6.7) | 54 (7.5) | |
| 1–2 | 79 (21.2) | 104 (27.9) | 183 (25.3) | |
| 2–3 | 129 (34.6) | 141 (37.8) | 270 (37.3) | |
| 4 or more | 114 (30.6) | 103 (27.6) | 217 (30.0) | 0.2475 |
| Age of first full-term pregnancy (yrs)b | ||||
| <20 | 108 (29.3) | 129 (34.6) | 237 (32.1) | |
| 21–25 | 129 (34.9) | 141 (37.8) | 270 (36.5) | |
| 26–30 | 87 (23.6) | 78 (20.9) | 162 (21.9) | |
| 31 | 45 (12.2) | 25 (6.7) | 70 (9.5) | 0.0356 |
a P was calculated by the χ2 test for heterogeneity (categorical variables) comparing cases with controls.
b Among parous women.