Table 1.
Distributions of selected characteristics by case-control status
| Variable | Cases (N = 441) N (%) | Controls (N = 479) N (%) | P-value |
|---|---|---|---|
| Age at menarche (years) | |||
| <11 | 27 (6.2) | 36 (7.5) | |
| 11–12 | 180 (41.4) | 190 (39.8) | |
| ≥12 | 228 (52.4) | 252 (52.7) | 0.693 |
| Menopausal status | |||
| Premenopausal | 103 (23.4) | 165 (34.5) | |
| Postmenopausal | 338 (76.6) | 314 (65.5) | 0.000 |
| Age at menopause (years) | |||
| <44 | 85 (26.0) | 104 (34.1) | |
| 44–49 | 117 (35.8) | 95 (31.2) | |
| >49 | 125 (38.2) | 106 (34.7) | 0.082 |
| Lifetime lactation (months) | |||
| 0 | 279 (63.3) | 291 (60.7) | |
| 1–5 | 55 (12.5) | 64 (13.4) | |
| 6–15 | 57 (12.9) | 67 (14.0) | |
| >15 | 50 (11.3) | 57 (11.9) | 0.890 |
| No. of live births | |||
| 0 | 54 (12.3) | 75 (15.7) | |
| 1–2 | 222 (50.5) | 218 (45.5) | |
| >2 | 164 (37.3) | 186 (38.8) | 0.203 |
| Age at first birth | |||
| <22 | 110 (28.5) | 124 (30.6) | |
| 22–26 | 154 (39.9) | 152 (37.5) | |
| >26 | 122 (31.6) | 129 (31.9) | 0.745 |
| Ethnicity | |||
| Caucasian | 401 (90.9) | 439 (91.6) | |
| African-American | 28 (6.4) | 28 (5.9) | |
| Other | 12 (2.7) | 12 (2.5) | 0.985 |
| Study site | |||
| New Haven County | 304 (68.9) | 313 (65.3) | |
| Tolland County | 137 (31.1) | 166 (34.7) | 0.247 |
| Family history of breast cancer in first-degree relatives | |||
| Yes | 103 (23.4) | 104 (21.7) | |
| No | 338 (76.6) | 375 (78.3) | 0.551 |