Table 1.
Baseline characteristics of ProF-SC participants, by breast cancer status at baseline and by loss to follow-up
|
Total cohort (
n
= 31640)
|
Affected at baseline (
n
= 12787)
|
Unaffected at baseline (
n
= 18853)
|
Lost to follow-up (
n
= 5728)
a |
|
|---|---|---|---|---|
| N or % or mean ± SD (min, max) | N or % or mean ± SD (min, max) | N or % or mean ± SD (min, max) | N or % or mean ± SD (min, max) | |
| BRCA1 mutation only | 1514 | 782 | 732 | 174 |
| BRCA2 mutation only | 1219 | 633 | 586 | 138 |
| BRCA1 & BRCA2 mutation | 8 | 8 | 0 | 1 |
| Year at recruitment | ||||
| 1992–94 | 1.7 | 1.1 | 2.0 | 0.6 |
| 1995–99 | 47.1 | 47.8 | 46.6 | 38.0 |
| 2000_04 | 30.2 | 29.8 | 30.5 | 35.0 |
| 2005–09 | 18.3 | 17.9 | 18.6 | 23.3 |
| 2010–30 June 2011 | 2.7 | 3.3 | 2.3 | 3.1 |
| Age at baseline (years) | 49.8 ± 14.8 | 52.9 ± 12.1 | 47.8 ± 16.1 | 48.8 ± 15.5 |
| (18, 101) | (21, 98) | (18, 101) | (18, 97) | |
| Number of first-degree relatives with breast cancer | 0.9 ± 0.8 | 0.6 ± 0.8 | 1.1 ± 0.7 | 0.9 ± 0.8 |
| (0, 6) | (0, 6) | (0, 6) | (0, 6) | |
| Number of second-degree relatives with breast cancer | 0.7 ± 0.9 | 0.6 ± 0.9 | 0.8 ± 1.0 | 0.7 ± 0.9 |
| (0, 11) | (0, 8) | (0, 11) | (0, 7) | |
| Body mass index (BMI) (kg/m 2 ) | 25.9 ± 5.6 | 26.2 ± 5.6 | 25.8 ± 5.6 | 26.2 ± 5.8 |
| Age at menarche (years) | 12.8 ± 1.6 | 12.7 ± 1.6 | 12.9 ± 1.6 | 12.8 ± 1.6 |
| Smoking status | ||||
| Never | 60.1 | 59.4 | 60.5 | 61.1 |
| Former | 26.9 | 28.3 | 25.9 | 23.3 |
| Current | 13.1 | 12.3 | 13.7 | 15.6 |
| Alcohol intake | ||||
| Never | 52.4 | 54.4 | 51.1 | 58.7 |
| Former | 14.3 | 13.4 | 14.9 | 14.1 |
| Current | 33.3 | 32.3 | 34.0 | 27.2 |
| Menopausal hormone use | ||||
| Never | 75.1 | 72.8 | 76.7 | 79.6 |
| Former | 16.9 | 24.5 | 11.8 | 13.9 |
| Current | 7.9 | 2.7 | 11.5 | 6.5 |
| Hormonal contraceptive use | ||||
| Never | 27.5 | 29.1 | 26.4 | 33.5 |
| Former | 64.1 | 69.3 | 60.5 | 58.5 |
| Current | 8.4 | 1.6 | 13.0 | 8.0 |
| Race/ethnicity | ||||
| Non-Hispanic White | 75.9 | 68.8 | 80.8 | 62.7 |
| Non-Hispanic Black | 6.2 | 8.6 | 4.6 | 8.7 |
| Hispanic | 9.4 | 11.2 | 8.1 | 15.1 |
| Asian | 5.8 | 8.8 | 3.8 | 10.2 |
| Other | 2.7 | 2.7 | 2.7 | 3.3 |
| Education | ||||
| ≤High school graduation / GED | 34.4 | 34.6 | 34.3 | 40.4 |
| Vocational or technical school / some college or university | 36.8 | 35.6 | 37.7 | 33.7 |
| Bachelor’s or graduate degree | 28.7 | 29.8 | 28.0 | 26.0 |
| Benign breast disease | ||||
| Yes | 31.0 | 36.3 | 27.4 | 26.7 |
| No | 69.0 | 63.7 | 72.6 | 73.3 |
| Parity | ||||
| 0 | 21.1 | 17.7 | 23.5 | 23.2 |
| 1 | 11.7 | 13.0 | 10.8 | 13.3 |
| 2 | 30.0 | 33.4 | 27.7 | 27.8 |
| 3 | 20.3 | 20.5 | 20.2 | 17.8 |
| ≥4 | 16.8 | 15.5 | 17.7 | 17.9 |
| Menopausal status | ||||
| Premenopausal | 45.1 | 30.3 | 55.3 | 49.9 |
| Postmenopausal | 54.9 | 69.7 | 44.7 | 50.1 |
a Includes refusals and not located.