Intact and total insulin-like growth factor-binding protein-3 (IGFBP-3) levels in relation to breast cancer risk factors: a cross-sectional study

Caroline Diorio , Jacques Brisson , Sylvie Berube and Michael Pollak

Breast Cancer Research 2008, 10:R42doi:10.1186/bcr2093


Published:	9 May 2008

Abstract (provisional)

Introduction

Levels of insulin-like growth factor (IGF)-I and its main binding protein (IGFBP-3) have been associated with breast cancer risk among premenopausal women. However, associations of IGFBP-3 levels with breast cancer risk have been inconsistent, possibly due to the different predominant forms of circulating IGFBP-3 (intact versus fragmented) that were measured in these studies. Here, we examine the association of breast cancer risk factors with intact and total IGFBP-3 levels.

Methods

This cross-sectional study includes 737 premenopausal women recruited at screening mammography. Plasma IGF-I, intact and total IGFBP-3 levels were measured by ELISA methods. Percent and absolute breast density were evaluated using a computer-assisted method. The associations were evaluated using generalized linear models and Pearson's (r) or Spearman's (rs) partial correlation coefficients.

Results

Means +/- standard deviations of intact and total IGFBP-3 levels (ng/mL) were 1044 +/- 234 and 4806 +/- 910, respectively. Intact and total IGFBP-3 levels were correlated with age and smoking. Levels of intact IGFBP-3 were negatively correlated with WHR (r = -0.128; P = 0.0005), parity (rs = -0.078; P = 0.04), alcohol intake (r = -0.137; P = 0.0002), and positively correlated with energy intake (r = 0.075; P = 0.04). In contrast, total IGFBP-3 levels were positively correlated with WHR (r = 0.115; P = 0.002), parity (rs = 0.089; P = 0.02), BMI (r = 0.115; P = 0.002), physical activity (r = 0.118; P = 0.002), IGF-I levels (r = 0.588; P < 0.0001), and negatively correlated with percent or absolute breast density (r = -0.095; P = 0.01 and r = -0.075; P = 0.04, respectively).

Conclusions

Our data show that associations of some breast cancer risk factors with intact levels of IGFBP-3 are different from those with total (intact and fragmented) IGFBP-3 levels. These findings suggest that different molecular forms of IGFBP-3 may bear different relations to premenopausal breast cancer risk.