Submitted by Shelley Francella, FMH Clinical Research Department
Metformin—Diabetes Medicine or Promising New Cancer Treatment?
The Canadian equivalent of our National Cancer Institute has opened an exciting new clinical trial looking at the role that the diabetes drug, metformin, may play in preventing breast cancer recurrence. The study, known as “MA-32” is based on information outlined below:
- Clinical evidence in the field of breast cancer research suggests that elevated fasting insulin levels are associated with poor breast cancer outcomes.
- Observational evidence suggests that metformin may reduce cancer risk in diabetics.
- Molecular evidence obtained in pre-clinical research indicates that metformin may be beneficial in preventing breast cancer activation.
Metformin is a well studied and relatively safe drug that has been used in the treatment of type II diabetes for many years. The most commonly seen side effects of metformin are gastrointestinal upset and slight weight loss.
The study is open to non-diabetic patients diagnosed with invasive breast cancer. Patients must have undergone their definitive surgical treatment within one year of beginning study treatment. Patients may receive standard treatment (chemotherapy, radiation, hormonal, or biological therapies) before or during study treatment. For patients who will receive chemotherapy, treatments must be completed before starting study treatment.
During their five years of study treatment, patients will take 850 mg metformin or placebo daily. The study is double blind, which means that neither the patient nor the physician will be informed of the treatment assignment.
Many times, people are troubled by the use of placebos (“sugar pills” or “dummy drugs”) in clinical trials. Using placebos is essential when researchers do not know whether or not a drug is beneficial. Researchers also must be able to impartially determine if the active drug is causing specific side effects. However, if, during the course of a clinical trial, evidence indicates the “active” drug is obviously of benefit, the study design would change, and all patients would quickly start to receive “active” drug.
The FMH Clinical Research Department is participating in this clinical study. If you would like to learn more about MA – 32, call the research office at 301-668-7043.