Table 3

Mean percentage of breast density, by IGF-I and IGFBP-3 quartiles (Q), among postmenopausal women

Model parametersMean percentage of breast density by IGF-I (ng/ml) quartilesSpearman correlation coefficienta (P)
Q1Q2Q3Q4
(40–136)(137–166)(167–222)(223–464)
Age and batch232326210.02 (0.84)
Age, IGFBP-3, and batch212326220.09 (0.29)
Age, IGFBP-3, alcohol intake, batch, BMI, and age at first birth212422200.01 (0.92)
Mean percentage of breast density by IGFBP-3 (ng/ml) quartiles
Q1Q2Q3Q4
(1930–3680)(3681–4275)(4276–4975)(4976–8240)Age and batch(4976–8240)
Age and batch25262219−0.10 (0.22)
Age, IGF-I, and batch25262219−0.13 (0.11)
Age, IGF-I, alcohol intake, batch, BMI, and age at first birth21262219−0.05 (0.52)
Mean percentage of breast density by IGF-I: IGFBP-3 (molar ratio) quartiles
Q1Q2Q3Q4
(0.070–0.120)(0.121–0.147)(0.148–0.182)(0.183–0.401)
Age and batch202625200.06 (0.42)
Age, alcohol intake, batch, BMI, and age at first birth22222419−0.02 (0.83)
  • Spearman correlation between the continuous measure of percentage of breast density and the continuous level of IGF-I or IGFBP-3. Adjusted correlations are partial Spearman coefficients.