Table 1. Age-standardized characteristics of the study population at benign breast biopsy by breast cancer case-control status in the Nurses’ Health Study and the Nurses’ Health Study II.
Values are means (SD) or percentages and are standardized to the age distribution of the study population. Values of polytomous variables may not sum to 100% due to rounding
| Controls (N=233) |
Casesa (N=69) |
|
|---|---|---|
| Stained for p27 expression in normal breast TDLUs | ||
| Percentage of p27+, median (IQR)* | 15.4 (25.0) | 16.1 (26.0) |
| Stained for ER expression in normal breast TDLUs | ||
| Percentage of ER+, median (IQR)* | 6.4 (12.0) | 5.0 (10.8) |
| Stained for Ki67 expression in normal breast TDLUs | ||
| Percentage of Ki67+, median (IQR)* | 0.77 (2.5) | 1.15 (2.7) |
|
| ||
| Age, years* | 44.6 (8.8) | 43.5 (9.0) |
| Type of benign lesion | ||
| -Non-proliferative, % | 28.2 | 23.1 |
| -Proliferative without atypia, % | 55.7 | 49.9 |
| -Proliferative with atypical hyperplasia, % | 16.1 | 27.0 |
| Height, inches | 64.6 (2.7) | 64.3 (2.1) |
| Average body size at ages 5–10 years | ||
| -Level 1 (most lean), % | 32.3 | 32.0 |
| -Level 1.5–2, % | 30.1 | 35.9 |
| -Level 2.5–3, % | 16.3 | 9.2 |
| -Level 3.5–4, % | 13.3 | 19.2 |
| -Level 4.5+ (most overweight), % | 8.0 | 3.7 |
| BMI at age 18 years, kg/m2 | 21.1(3.1) | 20.9(2.2) |
| BMI at biopsy, kg/m2 | 23.1(5.8) | 21.9(5.8) |
| Age at menarche, yrs | 12.6(1.4) | 12.3(1.3) |
| Parous at biopsy, % | 94.0 | 92.9 |
| Parity at biopsy (among parous women) | 3.1(1.5) | 3.2(1.6) |
| Age at first birth, years (among parous women) | 24.6(3.4) | 25.2(3.0) |
| Premenopausal, % | 74.9 | 74.2 |
| Age at menopause (among postmenopausal women at biopsy) | 45.5(7.2) | 47.2(4.4) |
| Ever oral contraceptive use | 51.0 | 61.2 |
| Ever Smoking | 50.4 | 66.3 |
| Family history of breast cancer, % | 17.0 | 29.8 |
| Adolescent alcohol drinker, % | 52.3 | 56.4 |
| Cumulative average lifetime alcohol consumptionb, g/d | 4.7(7.1) | 3.8(3.6) |
| Cumulative average adult physical activityc, MET-hr/wk | 15.9(19.1) | 11.2(9.9) |
a
Among 69 breast cancer cases, 54 cases were invasive cancers and 18 cases were in situ cancers. Among these 69 cases, 18 cases were ipsilateral, 25 cases were contralateral, and 8 cases were bilateral with respect to the index benign biopsies (the remaining 18 cases were from the unknown side of the breast).
*
Value is not age adjusted.
Abbreviations- BMI: body mass index, IQR: interquartile range, TDLU: terminal duct lobular unit