Metformin intervention in obese non-diabetic patients with breast cancer: phase II randomized, double-blind, placebo-controlled trial

Kwang Pil Ko, Seung Hyun Ma, Jae Jeong Yang, Yunji Hwang, Choonghyun Ahn, Young Min Cho, Dong Young Noh, Byung Joo Park, Wonshik Han, Sue K. Park

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

Previous observational studies have suggested that metformin in diabetes patients may reduce breast cancer risk more than the reductions from other anti-diabetes medications. This randomized, double-blind, placebo-controlled trial was performed to evaluate the efficacy of metformin for controlling physical and metabolic profiles related to prognosis and adverse events in non-diabetic breast cancer patients. Female breast cancer patients (N = 105), at least 6 months post-mastectomy, with obesity (≥25 kg/m2) and/or pre-diabetes (fasting blood sugar levels ≥100 mg/dL), were randomly assigned to three groups (placebo, metformin 500 mg, and metformin 1000 mg) stratified by tamoxifen use. A linear mixed model for repeated measurements among three groups and ANOVA for profile differences during 6 months of treatment were used for the intention-to-treat analysis. The metformin 1000 mg group had a significantly greater decline in glucose and HbA1c levels between treatment weeks 0 and 6 month (p = 0.008 and 0.009, respectively), and the declines increased with an increase in body mass index (BMI) level (p interaction with BMI = 0.007 and 0.067, respectively). A marginally significant different effect from the metformin 1000 mg treatment was detected for glucose and HbA1c levels (p interaction = 0.084 and 0.063, respectively) in the intention-to-treat analysis. Metformin 1000 mg treatment had a favorable effect on controlling glucose and HbA1C levels in obese non-diabetic breast cancer patients, indicating prognostic importance. Further trials are needed to elucidate the risk–benefit ratio of long-term use of metformin.

Original languageEnglish
Pages (from-to)361-370
Number of pages10
JournalBreast Cancer Research and Treatment
Volume153
Issue number2
DOIs
StatePublished - 7 Sep 2015

Keywords

  • Breast cancer
  • Glucose
  • Metformin
  • Postoperative adjuvant

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