Serum IGF-binding protein-6 and prostate specific antigen in breast cancer

Objective: Recent studies have demonstrated the presence of the IGF-binding proteins (IGFBPs) and prostate specific antigen (PSA), an IGFBP protease, in human breast tissue, We sought to investigate the differences in serum I GFs, IGFBP-1, 3 and -6, and PSA between patients with surgically proven bre ast cancer and patients with benign breast disease. Design ann Methods: Concentrations of IGFs, IGFBP-1, -3 and -6, and PSA wer e determined in the sera from 57 patients with breast cancer (CA), and 46 w omen with benign breast disease (BBD) using immunoassays for IGFs and IGFBP s and an ultrasensitive ELISA for PSA. Results: The mean (+/- S.E.M) serum IGFBP-6 level in the CA group, 127 (16) ng/ml, was statistically significantly lower than in the BED group, 157 (1 0) ng/ml (P = 0.016). Patients with CA had an elevated geometric mean serum PSA level of 0.018 (range: 0.0015-0.107) ng/ml, compared with 0.007 (range : 0.0015-0.019)ng/ml in women with BED (P = 0.025). Mean serum IGFBP-1 conc entrations were significantly lower in the CA group, 16 (2)ng/ml, versus 37 (4) ng/ml in the BED group (P = 0.001). Mean serum IGFBP-3 concentrations were also lower in the CA group versus the BED group, at 1981 (65) ng/ml, v ersus 2603 (140) ng/ml (P = 0.002) respectively. In the CA group, statistic ally significant correlations between PSA and IGFBP-6 (r = 0.413; P = 0.001 ), and between PSA and IGFBP-1 (r = -0.329; P = 0.021) were seen. Differenc es in IGF-I and II between the two groups were not statistically significan t. Conclusion: Lower serum concentrations of IGFBP-6, -3 and -1, but higher PS A concentrations were seen in the breast cancer group, and collectively the se would suggest that there is an increase in bioavailable IGF-I in breast cancer.