OU College of Medicine Researcher Explores Causes of Type 2 Diabetes After Breast Cancer Treatment

While today’s drugs help the majority of people with breast cancer survive for years, many who are treated eventually develop Type 2 diabetes, often years after treatment ends. A recent journal publication by a researcher at the University of Oklahoma College of Medicine at OU Health Sciences sheds light on the link between the two diseases and raises awareness for patients and physicians alike.

An article by researcher and assistant professor of pathology Elizabeth Wellberg, Ph.D., was published in Nature Reviews Endocrinology, a prestigious journal in the field. Because most breast cancers use the hormone estrogen to fuel their growth, drugs designed to block estrogen are highly effective for treating most types of the disease. However, the resulting decrease in estrogen may contribute to the development of diabetes in some people who had no indication of it before their breast cancer diagnosis.

“The data are crystal clear that these are lifesaving drugs for people diagnosed with breast cancer, and people should absolutely continue to take them according to their doctor’s recommendations,” Wellberg said. “But because these patients face a higher risk for developing diabetes, we can do more to monitor them and intervene earlier in order to prevent the onset of diabetes.”

Many drugs affect the body’s metabolism, but for this publication, Wellberg focuses on the drug tamoxifen and a group of drugs called aromatase inhibitors, which are frequently used to treat breast cancer. Both suppress estrogen signaling, thereby depriving cancer cells of what they need to replicate. However, estrogen plays a beneficial role in many other ways, including bone health, brain health and body composition.

“Estrogen affects every tissue in the body,” Wellberg said. “When you give a drug, it’s not only going to the tumor, it’s going everywhere, so it’s no wonder there are whole-body effects from the loss of estrogen.”

In this article, Wellberg reviews the history of the drugs and hypothesizes about what may be happening to spark the development of diabetes. In her own laboratory, she has demonstrated that the drugs change the metabolism of mice in a way that is similar to prediabetes in humans.

Much more research is needed to identify which patients treated for breast cancer face the highest risk for developing diabetes, and to better understand how the drugs are paving the way for the development of diabetes in some people. But in the meantime, the evidence is strong enough to prompt increased awareness among both patients and health care providers.

“The nice thing is that we already have programs and interventions to prevent diabetes,” Wellberg said. “Exercise and dietary programs are effective, and the drug metformin can prevent or delay diabetes. Implementing these interventions could be relatively rapid once we know who is at risk during breast cancer treatment. Not everyone who is treated for breast cancer ends up developing diabetes, but it’s not rare. Because people treated for breast cancer are surviving longer than they ever have, we are becoming more aware of other conditions they may face because of the treatment they received. If people notice their metabolism changing or they are gaining weight, they should tell their doctor. Likewise, an integrated care team of oncologists and endocrinologists ideally can work together to identify and prevent potential problems earlier in the treatment process.”

Wellberg’s article, “Diabetes mellitus in breast cancer survivors: metabolic effects of endocrine therapy,” can be found at nature.com/nrendo. Additional authors on the publication are Nisha Thomas, Ph.D., a post-doctoral researcher in the Department of Pathology in the OU College of Medicine, and Rebecca Scalzo, Ph.D., an endocrinology researcher at the University of Colorado Anschutz Medical Campus in Aurora, Colorado.

About the OU College of Medicine
Founded in 1910, the OU College of Medicine at the University of Oklahoma Health Sciences trains the next generation of health care professionals. The OU Health Sciences is the academic partner of OU Health, the state’s only comprehensive academic health system of hospitals, clinics and centers of excellence. With campuses in Oklahoma City and Tulsa, the College of Medicine offers the state’s only Doctor of Medicine degree program and a nationally competitive Physician Assistant program. For more information, visit medicine.ouhsc.edu.

About the University of Oklahoma Health Sciences
The University of Oklahoma Health Sciences is one of the nation’s few academic health centers with all health professions colleges — Allied Health, Dentistry, Medicine, Nursing, Pharmacy, Public Health, Graduate Studies and School of Community Medicine. OU Health Sciences serves approximately 4,000 students in more than 70 undergraduate and graduate degree programs on campuses in Oklahoma City and Tulsa and is the academic and research partner of OU Health, the state’s only comprehensive academic healthcare system. The OU Health Sciences is ranked 129 out of over 2,849 institutions in funding received from the National Institutes of Health, according to the Blue Ridge Institute for Medical Research. For more information, visit ouhsc.edu.

About the University of Oklahoma
Founded in 1890, the University of Oklahoma is a public research university located in Norman, Oklahoma. As the state’s flagship university, OU serves the educational, cultural, economic and health care needs of the state, region and nation. OU was named the state’s highest-ranking university in U.S. News & World Report’s most recent Best Colleges list. For more information about the university, visit ou.edu.