Metformin May Lower the Risk of Cancer in Post-Menopausal Women with Diabetes

Women taking metformin for diabetes were less likely to develop cancer or experience cancer-related death than women not taking the drug.

Researchers have found that women with diabetes were more likely to develop cancer, however, patients taking metformin had a decreased risk of cancer, as well as a decreased risk of cancer-related death, according to a study published by the International Journal of Cancer.

Based on data from the Women’s Health Initiative (WHI) from 1993 to 1998, researchers analyzed outcomes from 145,826 post-menopausal women.

Women with diabetes showed a 13% higher risk of being diagnosed with invasive cancer than women without diabetes. This study found that patients with diabetes had a 45% greater risk of invasive cancer-related death than those without diabetes.

Researchers noted that there was a significant difference between patients who used metformin and those who did not. There was a decreased risk of cancer-related death associated with increased metformin use, as well.

According to this study, metformin use was also associated with better survival rates in ovarian, colorectal, and breast cancers.

"In this large prospective study with long-term follow-up, we examined the association of diabetes and medications to treat the disease with the risk of cancer and cancer mortality overall and by cancer site," said lead researcher Zhihong Gong, PhD. "Our findings suggest that diabetes remains a risk factor for cancer overall and increases the risk of certain cancers. But we also found a lower cancer risk for certain cancers among those patients who have used metformin for many years."

Additional research is needed to determine the long-term effects of metformin on cancer risk and survival rates, the study concluded.