201. Dual effect of metformin on breast cancer proliferation in a randomized presurgical trial.
- Author
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Bonanni B, Puntoni M, Cazzaniga M, Pruneri G, Serrano D, Guerrieri-Gonzaga A, Gennari A, Trabacca MS, Galimberti V, Veronesi P, Johansson H, Aristarco V, Bassi F, Luini A, Lazzeroni M, Varricchio C, Viale G, Bruzzi P, and Decensi A
- Subjects
- Adult, Aged, Antineoplastic Agents administration & dosage, Biomarkers, Tumor analysis, Biomarkers, Tumor blood, Blood Glucose drug effects, Breast Neoplasms blood, Breast Neoplasms chemistry, Breast Neoplasms surgery, Double-Blind Method, Drug Administration Schedule, Female, Humans, Hypoglycemic Agents pharmacology, Immunohistochemistry, Insulin Resistance, Italy, Ki-67 Antigen blood, Metformin administration & dosage, Middle Aged, Antineoplastic Agents pharmacology, Breast Neoplasms drug therapy, Breast Neoplasms pathology, Cell Proliferation drug effects, Metformin pharmacology, Neoadjuvant Therapy methods
- Abstract
Purpose: Metformin is associated with reduced breast cancer risk in observational studies in patients with diabetes, but clinical evidence for antitumor activity is unclear. The change in Ki-67 between pretreatment biopsy and post-treatment surgical specimen has prognostic value and may predict antitumor activity in breast cancer., Patients and Methods: After tumor biopsy, we randomly allocated 200 nondiabetic women with operable breast cancer to either metformin 850 mg/twice per day (n = 100) or placebo (n = 100). The primary outcome measure was the difference between arms in Ki-67 after 4 weeks adjusted for baseline values., Results: Overall, the metformin effect on Ki-67 change relative to placebo was not statistically significant, with a mean proportional increase of 4.0% (95% CI, -5.6% to 14.4%) 4 weeks apart. However, there was a different drug effect depending on insulin resistance (homeostasis model assessment [HOMA] index > 2.8, fasting glucose [mmol/L] × insulin [mU/L]/22.5; P(interaction) = .045), with a nonsignificant mean proportional decrease in Ki-67 of 10.5% (95% CI, -26.1% to 8.4%) in women with HOMA more than 2.8 and a nonsignificant increase of 11.1% (95% CI, -0.6% to 24.2%) with HOMA less than or equal to 2.8. A different effect of metformin according to HOMA index was noted also in luminal B tumors (P(interaction) = .05). Similar trends to drug effect modifications were observed according to body mass index (P = .143), waist/hip girth-ratio (P = .058), moderate alcohol consumption (P = .005), and C-reactive protein (P = .080)., Conclusion: Metformin before surgery did not significantly affect Ki-67 overall, but showed significantly different effects according to insulin resistance, particularly in luminal B tumors. Our findings warrant further studies of metformin in breast cancer with careful consideration to the metabolic characteristics of the study population.
- Published
- 2012
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