Serum levels of insulin-like growth factor binding protein-3 in benign and malignant breast disease.
BACKGROUND
The insulin-like growth factors IGF-I and IGF-II and their major binding protein IGFBP-3 influence the growth of breast cancer cells in vitro. Some benign non-breast tumours appear to be associated with increased serum IGFBP-3 levels which would tend to reduce bioactive-free IGF concentrations. The present study investigates whether this pattern also occurs in neoplastic breast disease.


METHODS
Serum IGF-I, IGF-II and IGFBP-3 were measured by specific radioassay in 12 women with benign breast disease, 31 patients with breast cancer and in age-matched controls.


RESULTS
The mean (+/-SD) serum IGFBP-3 concentration was higher in benign breast disease (3.6+/-0.7 mg/L) than in controls (2.7+/-0.6 mg/L) or in breast cancer patients (2.7+/-0.5 mg/L) (P = 0.001). Serum IGF-I and IGF-II levels were not significantly different among the groups. However, the index of free unbound IGF measured as the molar ratio of IGF-I plus IGF-II divided by IGFBP-3 was significantly lower in benign breast disease than in the other subjects.


CONCLUSIONS
Either the production or clearance of IGFBP-3 is altered in benign breast disease so that there is less free IGF available to cells. This may serve to protect against malignant transformation in patients with benign breast disorders.
Holdaway
I M
IM
Department of Endocrinology, School of Medicine, Auckland University, New Zealand. ian@ahsl.co.nz
Mason
B H
BH
Lethaby
A E
AE
Singh
V
V
Harman
J E
JE
MacCormick
M
M
Civil
I D
ID
D000328:Adult; D001941:Breast Diseases / Q000097:blood*; D001943:Breast Neoplasms / Q000097:blood* / Q000473:pathology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000378:metabolism; D008875:Middle Aged
D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II