Table 1.
Characteristics of study population by case-control status.
| Characteristic | Cases (n = 200) | Controls (n = 360) | P-value* |
|---|---|---|---|
| Age (years), mean (SD) | 52.7 (10.9) | 54.2 (10.2) | 0.11 |
| Race, N (%) | |||
| White | 147 (73) | 224 (62) | |
| Black | 42 (21) | 126 (35) | |
| Other | 11 (6) | 10 (3) | <0.01 |
| BMI, mean (SD) | 27.1 (6.4) | 27.7 (7.2) | 0.26 |
| Active smoking, N (%) | |||
| Ever | 71 (36) | 148 (41) | 0.2 |
| Age at menarche (years), mean (SD) | 12.6 (1.5) | 12.5 (1.5) | 0.58 |
| Ever pregnant, N (%) | |||
| Yes | 161 (81) | 288 (80) | 0.67 |
| FTP (N), mean (SD) | 1.61 (1.2) | 2.00 (1.2) | <0.01 |
| Age at 1st FTP (years), mean (SD) | 27.3 (6.3) | 27.4 (6.6) | 0.97 |
| Age at last FTP (years), mean (SD) | 31.7 (6.1) | 32.0 (5.8) | 0.63 |
| Years since last FTP (years), mean (SD) | 22.7 (13.3) | 23.1 (12.1) | 0.75 |
| Ever breastfed (%) | |||
| Yes | 82 (66) | 178 (69) | 0.43 |
| Weeks breastfed (N), mean (SD) | 56.6 (66.7) | 70.0 (70.1) | 0.13 |
| Menopausal Status, N (%) | |||
| Post- | 108 (56) | 218 (61) | 0.23 |
| Use of HRT (%) | |||
| Ever | 53 (51) | 120 (55) | 0.54 |
| Physical activity at age 13–19, N (%) | |||
| Yes | 130 (65) | 277 (79) | <0.01 |
| Family history of female cancers, N (%) | |||
| 0 relatives affected | 180 (90) | 329 (93.7) | |
| 1 relative affected | 9 (4.5) | 21 (6) | |
| 2 relatives affected | 1 (0.5) | 1 (0.3) | 0.76 |
| Educational level (%) | |||
| Equal/above college | 80 (40) | 153 (43) | 0.63 |
| Household income (%) | |||
| Equal/above $100K | 78 (56) | 134 (52) | 0.38 |
Notes: P-values were computed using t-tests for continuous characteristics and chi-square tests for categorical characteristics. Missing values were excluded from the P-value computation. Physical activity was defined as any weekly physical activity, longer than 20 minutes at a time that would make the subject sweat or increase their heart rate. Family history of female cancers was defined as any breast or ovarian cases among 1st and 2nd degree blood relatives.
Abbreviations: BMI, body mass index; FTP, full term pregnancy, analyses among parous women only; HRT, hormonal replacement therapy, analysis among post-menopausal women, weeks breastfeeding computed only among women that breastfed.