Download Effect of different doses of Metformin on serum testosterone and

Effect of different doses of Metformin on serum testosterone and insulin in non-diabetic
women with breast cancer: a randomized study
Carlo CAMPAGNOLI, Patrizia PASANISI, Chiara ABBÀ, Simona AMBROGGIO, Nicoletta BIGLIA, Tiziana
BRUCATO, Raffaella COLOMBERO, Saverio DANESE, Michela DONADIO, Elisabetta VENTURELLI, Gianna
ZITO and Franco BERRINO
Clinical Breast Cancer 2012
Abstract
Background Serum levels of insulin and testosterone may affect both breast cancer (BC) incidence
and prognosis. Metformin reduces hyperglycemia and insulin in diabetic patients. In non-diabetic
women with polycystic ovary syndrome, Metformin lowers both insulin and testosterone.
Metformin-treated diabetic patients show a lower risk of cancer, and a protective effect of
Metformin was observed also for BC. Recently, studies on Metformin use against BC have been
proposed in non-diabetic patients.
The aim of the present study was to test the effect of different doses of Metformin on serum levels
of insulin and testosterone in non-diabetic post-menopausal BC patients with basal testosterone
levels ≥ 0.28 ng/mL (median value).
Patients and Methods 125 eligible women were initially invited to take 500 mg Metformin/day for
3 months. The 108 women who completed the first three months were invited to continue the study
with 1000 mg Metformin/day (500 x 2) for one month. Women were then randomized into two
groups, and for the subsequent 5 months one group increased the dose, taking 1500 mg
Metformin/day (500 x 3), and the other group continued with 1000 mg Metformin/day (500 x 2).
Results 96 women completed the study, 43 women receiving 1500 mg/day, and 53 1000 mg/day.
The women who took 1500 mg/day showed a significant reduction of insulin, HOMA-IR index,
testosterone and free androgen index compared with women treated with 1000 mg/day. After
treatment with 1500 mg/day, insulin decreased by 25% and testosterone decreased by 23%.
Conclusion Both these changes might have a prognostic importance.
1