Evaluation of insulin-like growth factor-I in postmenopausal women with breast cancer treated with raloxifene.

BACKGROUND: The objective of this study was to evaluate serum IGF-I levels in postmenopausal women with breast cancer treated primarily with raloxifene. METHODS: Twenty-two postmenopausal patients with operable, stage I or II, estrogen receptor-positive carcinomas participated in this study. Following confirmation of diagnosis, the patients received 60 mg of raloxifene for 28 days prior to definitive surgery. Blood samples were collected for evaluation of serum IGF-I levels prior to initiating medication and following a 28-day treatment course. Student's t-test for paired samples was used in the statistical analysis. Significance was established at p < 0.05. RESULTS: Mean serum IGF-I levels pre- and post-raloxifene treatment were 143.7 +/- 9.7 ng/ml and 94.8 +/- 7.6 ng/ml, respectively. This reduction in serum IGF-I levels following treatment with raloxifene was statistically significant (p < 0.001). CONCLUSION: Raloxifene significantly reduced serum IGF-I levels in postmenopausal women with breast cancer.