Effect of two 4-hydroxyandrostenedione doses on serum insulin-like growth factor I levels in advanced breast cancer

A number of endocrine treatments for advanced breast cancer seem to affect serum insulin-like growth factor I (IGF-I). The aim of our study was to investigate IGF-I levels in 33 postmenopausal patients with metastatic disease receiving the selective aromatase inhibitor 4-hydroxyandrostenedione: 250 mg (16 patients) or 500 mg (17 patients) i.m. fortnightly. Blood samples were collected before, and at one month and 3 months after the beginning of treatment for radioimmunoassay determinations. The median patient age was 56 and 60 years in the 250 and 500 mg groups respectively. Most patients had a disease free interval ≥ 2 years and were oestrogen receptor positive. Objective responses were obtained in 3 patients (complete response, 1) in the 250 mg group, and in 7 patients (complete response, 3) in the 500 mg group. No significant IGF-I variations were seen in the 250 mg group, whereas a significant increase after 3 months (181.57 ± 84.78 ng/mlversus 272.47 ± 213.22 ng/ml, p = 0.0032) was observed in the 500 mg group. No IGF-I variations were seen between responsive and unresponsive patients in either treatment group. Our results in the 500 mg group are close to those obtained with aminoglutethimide and seem to agree with the hypothesis of an oestrogen-induced suppression of IGF-I circulating levels.