medwireNews: Researchers recommend the use of the antidiabetic agent metformin for the subset of women with human epidermal growth factor receptor (HER2)-positive and hormone receptor-positive breast cancer who also have diabetes.
They conducted a post hoc analysis of the ALTTO trial, which had been conceived to evaluate lapatinib in the adjuvant setting, and included 8381 patients, of whom 2.2% had not received metformin for diabetes and 3.1% had.
Compared with nondiabetic patients, those with diabetes who were not prescribed metformin had significantly worse disease-free survival, distant disease-free survival, and overall survival, with adjusted hazard ratios of 1.40, 1.56, and 1.87, respectively.
However, such an association was not evident among patients with diabetes who received metformin, report Evandro de Azambuja (Institut Jules Bordet in Brussels, Belgium) and colleagues.
Furthermore, the increased risk for poor survival among women not prescribed metformin was restricted to those with hormone receptor-positive disease.
The team concludes in the Journal of Clinical Oncology: “Despite the lack of level one evidence, we believe that for patients with diabetes and HER2-positive and hormone receptor–positive disease, it is reasonable to recommend metformin treatment if patients have not already received treatment.”
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