A study from researchers at Roswell Park Cancer Institute and the University at Buffalo (both NY, USA) has reported that long-term metformin use to treat diabetes in postmenopausal women lowers the risk of both developing certain types of cancer and of dying from these diseases.
The large prospective study, published recently in the International Journal of Cancer, was based on data from the Women’s Health Initiative (WHI), and was led by Zhigong Gong (Assistant Professor of Oncology at Roswell Park Cancer Institute) and Jean Wactawski-Wende (one of the Principal Investigators of the WHI and Dean of the School of Public Health and Health Professions at the University at Buffalo).
The team analyzed data on 145,826 postmenopausal women aged between 50 and 79 years of age, from a total of 40 US clinical centers, who had participated in the WHI between 1993 and 1998. First, their results showed that diabetic women had a 45% increased risk of dying from invasive cancer than women without diabetes. Second, they showed that use of metformin among the women with diabetes affected their risk of cancer death – risk of ovarian, colorectal and breast cancer death decreased with increasing duration of metformin use.
Gong commented: “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 … 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.”
“The WHI continues to offer thoughtful, meaningful data to researchers seeking to answer health care questions that impact our understanding of long-term health in older women,” commented Wactawski-Wende.
The team concluded that the long-term effect of metformin on cancer risk and survival needs to be further clarified by future studies.