
“Deborah agreed to take part in a trial as she was keen to help other cancer patients in the future. "If taking part in a trial means others might be helped then I’m very happy with that."
Please note - this trial is no longer recruiting patients. We hope to add results when they are available.
This trial is testing the drug metformin for early breast cancer. This trial is supported by Cancer Research UK.
Metformin works by lowering blood levels of a hormone called . We know from research that people with breast cancer who have low insulin may do better than those with high levels of insulin. We also know from
that metformin may slow the growth of some cancers, including breast cancer.
The aim of this trial is to find out if adding metformin to standard treatment can help people with breast cancer live longer.
You may be able to enter this trial if you are female and
You cannot enter this trial if
This is an international phase 3 trial. It will recruit 3,580 women from different countries around the world. This is a randomised trial. The people taking part are put into 1 of 2 treatment groups by a computer. Neither you nor your doctor will be able to decide which group you are in. And neither of you will know which group you are in either. This is called a double blind trial.
The women in group 1 will have metformin for 5 years. The women in group 2 will have a dummy drug (placebo) for 5 years. Both metformin and the dummy drug are tablets. You take 1 tablet daily for 4 weeks. You then take 2 tablets a day, 1 in the morning and 1 tablet in the evening. You take your tablets with food.
If you agree to take part in this trial you will have 3 extra blood tests to measure how much sugar and insulin is in your blood (a fasting blood test). Before these blood tests you must not eat or drink anything other than water for 12 hours.
If you agree to take part in this study, the researchers will ask for a sample of tissue taken from when you had surgery to remove your cancer. If you don’t want to give tissue samples for this study, you don’t have to. You can still take part in the trial.
You see the doctor before taking part in this trial and have some tests. These tests may include
During treatment you see the doctor after 6 months, 1 year and then once a year after that. You have a physical examination and blood tests at each appointment. You have a fasting blood test at 6 months and 5 years. You have a mammogram every year.
The most common side effects of metformin are
Please note: In order to join a trial you will need to discuss it with your doctor, unless otherwise specified.
Prof Alastair Thompson (in the UK)
Cancer Research UK
Experimental Cancer Medicine Centre (ECMC)
Institute of Cancer Research (ICR)
National Institute for Health Research Cancer Research Network (NCRN)
This is Cancer Research UK trial number CRUK/11/034.
If you have questions about the trial please contact our cancer information nurses
Freephone 0808 800 4040
“Deborah agreed to take part in a trial as she was keen to help other cancer patients in the future. "If taking part in a trial means others might be helped then I’m very happy with that."