Patients with diabetes are thought tobe at increased risk of developing certain types of cancer, as well as being at an increased risk of developing a recurrence of previously diagnosed cancers. For example, an increased risk of recurrent breast cancer has, specifically, been linked to obesity and diabetes in women.
Among other possible explanations, elevated levels of insulin are thought to act as a stimulus for cancer cells to grow and divide. Other diabetes-associated molecules also appear to cause increased cancer cell proliferation, or growth, including insulin-like growth factor (IGF).
Metformin, also known as Glucophage, has become the most commonly prescribed oral medication for the treatment of diabetes. Previous laboratory and public health studies have suggested that metformin may also be able to suppress cancer cell proliferation, and to reduce the risk of death due to cancer. However, thus far, there has been very little direct clinical research evidence available to support this hypothesis.