Israeli researchers find diabetes drug may ward off breast cancer

Can medicine that helps diabetes also benefit breast cancer?

Hadassah Medical Center (photo credit: WWW.HADASSAH.ORG.IL)
Hadassah Medical Center
(photo credit: WWW.HADASSAH.ORG.IL)
A drug commonly used to treat type-2 diabetes can prevent or delay the recurrence of some types of breast cancer, researchers at Hadassah-University Medical Center have found.
Metformin (Glucophage and other brand names) was found in a study of 8,000 patients around the world to reduce the risk of repeated HER-2 positive breast cancers.
HER2-positive breast cancers tend to grow faster and are more likely to spread and come back compared to HER2-negative breast cancers.
The research appeared in the Journal of Clinical Oncology.
The study, led by Hadassah oncologist Dr. Amir Sonnenblick, offers encouraging results for women with HER2-positive (human epidermal growth factor receptor 2) breast cancer, as metformin was found beneficial to women with type-2 diabetes as well as this aggressive type of malignancy.
“Until now there have been preclinical studies in the field – using lab cultures and mice.
They showed that administering metformin and related diabetes drugs to mice may prevent or delay recurrence of breast cancer, while not giving the drug can raise the risk for the return of the malignancy,” said Sonnenblick. But this was the first significant study using women as subjects.
The researchers also found that giving insulin to HER2+ patients more than doubled the risk of a breast cancer recurrence, while metformin had the opposite result.
Thus, the international team concluded that careful dosage of such patients could have a dramatic effect in protecting women with this highrisk type of breast cancer.
A graduate of the Hebrew-University Medical Faculty who did his oncology residency at the Jerusalem medical center, Sonnenblick also spent time at the Institut Jules Bordet, the only autonomous hospital in Belgium completely dedicated to cancer.
A total of 8,381 patients were included in the study: 7,935 patients (94.7%) had no history of diabetes at diagnosis, 186 patients (2.2%) had diabetes with no metformin treatment, and 260 patients (3.1%) were diabetic and had been treated with metformin.
Patients with diabetes and HER-2 positive breast cancer who had not been treated with metformin experienced worse multivariable hazard than those who had. “Metformin may improve the worse prognosis that is associated with diabetes and insulin treatment, mainly in patients with primary HER2-positive and hormone receptor-positive breast cancer,” the team concluded.
The other researchers came from the UK, Italy, Brussels, US, Denmark, Switzerland, Chile, Japan, Ireland, Brazil, Slovenia and the Netherlands.