Table 1.
Characteristics of breast cancer cases and matched controls at blood collection in the Nurses’ Health Study II
| Characteristic | Cases (n=610) | Controls (n=1207) |
|---|---|---|
| Mean (SD) | Mean (SD) | |
| Age (years) | 45.0 (4.4) | 44.9 (4.4) |
| Age at menarche (years) | 12.4 (1.3) | 12.4 (1.4) |
| Age at first birth * (years) | 26.5 (4.6) | 26.2 (4.6) |
| Parity * | 2.2 (0.9) | 2.3 (0.9) |
| Body mass index at age 18 (kg/m2) | 20.7 (2.7) | 21.1 (3.0) |
| Body mass index at blood collection | 25.2 (4.9) | 25.9 (6.1) |
| (kg/m2) | ||
| Alcohol Intake (g/day) | 4.1 (7.1) | 3.5 (6.3) |
| Age at menopause (years) | 43.2 (5.2) | 42.4 (3.8) |
| % | % | |
| Family history of breast cancer | 28 | 17 |
| Personal history of benign breast disease | 56 | 49 |
| Current use of multivitamins | 44 | 44 |
| Postmenopausal | 13 | 15 |
| Postmenopausal hormone use, current† | 89 | 83 |
| Plasma measures | Median (5–95th percentile) | Median (5–95th percentile) |
| Folate (ng/mL) | 16.4 (7.1–32.8) | 16.0 (6.0–33.2) |
| Vitamin B12 (pg/mL) | 443 (221–1012) | 424 (207–896) |
| Pyridoxal 5’-phosphate (pmol/mL) | 49.9 (19.8–321.5) | 48.8 (19.9–272.9) |
| Homocysteine (nmol/mL) | 9.3 (6.0–15.1) | 9.2 (6.2–15.0) |
| Cysteine (nmol/mL) | 244.1 (195.5–310.7) | 242.7 (191.8–315.9) |
| Cysteinylglycine (nmol/mL) | 243.8 (163.8–369.7) | 245.5 (159.3–376.8) |
| Dietary intake | Median (5–95th percentile) | Median (5–95th percentile) |
| Total folate (μg/day) | 366 (185–941) | 366 (176–929) |
| Folate from foods only (μg/day) | 290 (178–506) | 290 (170–488) |
| Total Bn (μg/day) | 7.0 (3.0–23.0) | 7.0 (3.0–21.0) |
| B12 from foods only (μg/day) | 5.2 (2.7–12.0) | 5.2 (2.7–10.8) |
| Total B6 (mg/day) | 2.5 (1.5–55.8) | 2.5 (1.5–43.4) |
| B6 from foods only (mg/day) | 2.0 (1.5–3.0) | 2.0 (1.5–2.8) |
*
Among parous women only
†
Among postmenopausal women only