Table 5.
Relative risks and 95% confidence intervals (CI) of invasive breast cancer for models that incorporate both the 1990 and 2000 plasma measures
| Tertile of plasma measure | p for trend | Per 1-SD increase in natural log-transformed concentrations | |||
|---|---|---|---|---|---|
| 1 (lowest) | 2 | 3 | |||
| Average of 1990 and 2000 plasma measures1 | |||||
| Folate, ng/mL | <11.6 | 11.6 to 18.4 | ≥18.5 | ||
| 1.00 (ref) | 0.79 (0.53, 1.17) | 1.38 (0.94, 2.03) | 0.03 | 1.20 (1.00, 1.44) | |
| Vitamin B12, pg/mL | <415 | 415 to 612 | ≥613 | ||
| 1.00 (ref) | 1.02 (0.70, 1.49) | 0.97 (0.66, 1.41) | 0.83 | 1.03 (0.88, 1.22) | |
| Pyridoxal 5′-phosphate, pg/mL | <33.7 | 33.7 to 57.7 | ≥57.8 | ||
| 1.00 (ref) | 0.79 (0.54, 1.15) | 1.06 (0.72, 1.54) | 0.59 | 1.06 (0.88, 1.27) | |
| Homocysteine, nmol/mL | <9.5 | 9.5 to 11.2 | ≥11.3 | ||
| 1.00 (ref) | 0.80 (0.54, 1.19) | 1.17 (0.80, 1.73) | 0.34 | 1.09 (0.88, 1.33) | |
| Cysteine, nmol/mL | <229.6 | 229.6 to 240.6 | ≥240.7 | ||
| 1.00 (ref) | 1.36 (0.92, 2.00) | 1.15 (0.75, 1.77) | 0.53 | 1.19 (0.97, 1.46) | |
| Cysteinylglycine, nmol/mL | <171.0 | 171.0 to 210.3 | ≥210.4 | ||
| 1.00 (ref) | 0.78 (0.54, 1.15) | 0.84 (0.57, 1.22) | 0.37 | 0.93 (0.78, 1.11) | |
| Updated plasma measures2 | |||||
| Folate, ng/mL | 1.00 (ref) | 1.04 (0.88, 1.22) | 0.93 (0.79, 1.10) | 0.52 | 0.97 (0.90, 1.04) |
| Vitamin B12, pg/mL | 1.00 (ref) | 1.11 (0.94, 1.30 | 0.95 (0.80, 1.12) | 0.49 | 1.02 (0.94, 1.09) |
| Pyridoxal 5′-phosphate, pg/mL | 1.00 (ref) | 0.95 (0.81, 1.12) | 0.93 (0.79, 1.10) | 0.42 | 0.98 (0.92, 1.05) |
| Homocysteine, nmol/mL | 1.00 (ref) | 0.91 (0.77, 1.08) | 1.16 (0.98, 1.37) | 0.08 | 1.08 (1.01, 1.15) |
| Cysteine, nmol/mL | 1.00 (ref) | 1.07 (0.91, 1.27) | 0.99 (0.83, 1.18) | 0.15 | 0.98 (0.92, 1.06) |
| Cysteinylglycine, nmol/mL | 1.00 (ref) | 0.84 (0.71, 0.98) | 0.89 (0.76, 1.06) | 0.37 | 0.95 (0.88, 1.02) |
Unconditional logistic regression using the average of the 1990 and 2000 plasma measures among only those with two blood collections (2000–2006 follow-up; Cases/Controls:367/367) with adjustments for matching factors, age at menarche (continuous variable), parity/age at first birth (nulliparous, 1–2 children/first birth <25 years, 1–2 children/first birth 25+ years, ≥3 children/first birth <25 years, ≥3 children/first birth 25+ years), age at menopause (<50, ≥50 to <55, or ≥ 55 years), family history of breast cancer in mother or a sister (yes or no), history of benign breast disease (yes or no), height (continuous), body mass index at 18 (<21, 21 to <23, 23+), weight change from age 18 (continuous) and alcohol intake at blood collection (continuous) in both 1990 and 2000.
Repeated measures logistic regression, where 1990 plasma measure used for 1990–2000 time period and the 2000 plasma measure for the 2000–2006 time period (Cases/Controls:1626/1855). Controls from the 2000–2006 case–control pairs were allowed to contribute to both the 1990–2000 and 2000–2006 time periods. Models were adjusted for matching factors, age at menarche (continuous variable), parity/age at first birth (nulliparous, 1–2 children/first birth <25 years, 1–2 children/first birth 25+ years, ≥3 children/first birth <25 years, ≥3 children/first birth 25+ years), age at menopause (<50, ≥50 to <55, or ≥ 55 years), family history of breast cancer in mother or a sister (yes or no), history of benign breast disease (yes or no), height (continuous), body mass index at 18 (<21, 21 to <23, 23+), weight change from age 18 (continuous) and alcohol intake (continuous), updated at time of blood collection when relevant. See Table 4 for blood collection specific tertile cut points.