Rao M, et al. - In patients with cancer and diabetes mellitus (DM), researchers assessed the radiotherapy effectiveness of metformin. They included studies that involved comparisons of the short-term tumor responses and long-term survival outcomes of these patients who were managed with or without metformin as well as of nondiabetic patients without metformin. In patients with cancer and DM, metformin improves the tumor response to radiotherapy and partly offers survival benefits. Risk of bias was seen in these retrospective data, despite the apparent advantages provided by metformin treatment on 2 year-OS and 5 year-OS, and should be interpreted with caution. They noted no significant difference in the metformin-related HRs of OS values.