Scientist in the Spotlight: Excess Body Fat, Menopause and Increased Breast Cancer Risk
Excess body fat increases the risk of cancer, yet that risk may vary depending upon when in life we carry the excess fat, says Erin Giles, PhD. With AICR support, Giles' lab work is unraveling the mechanisms behind why obesity may heighten breast cancer risk during certain windows of time.
After completing her undergraduate degree in biomedical science, Giles applied to the graduate program in medical science at McMaster University in Hamilton, Canada. When asked to list a few key words on the application to describe her research interests, she listed “cancer” and “bone,” not knowing the inclusion of these words would end up shaping the course of her career.
“At the time, I didn’t think of cancer and bone as being connected, but it lead me to an interview with a faculty member at McMaster who studied breast cancer metastasis,” said Giles. “While getting into this field occurred somewhat by chance for me, I knew after earning my doctoral degree I wanted to conduct integrative research that was translational in focus.”
Giles, now a Postdoctoral Fellow at the Center for Human Nutrition at the University of Colorado, does exactly that by exploring the link between menopause, weight gain and breast cancer using a rodent model of obesity and postmenopausal breast cancer.
Linking Weight Gain at Menopause to Cancer
She recently published a study in Cancer Research comparing how lean and obese rats differed in their responses to weight gain after ovary removal. In contrast to lean rats, obese rats were unable to metabolize excess calories into their healthy tissues, causing the extra glucose and fat to fuel tumor growth. The researchers also found higher levels of the progesterone receptor, linked to tumor growth and the uptake of glucose, in tumors from obese rats. When the researchers treated the obese rats with the anti-diabetic drug metformin, they were able to improve glucose control and the ability of normal tissue to metabolize excess calories.
“Obesity is a growing problem worldwide, and being overweight or obese increases the risk of developing several types of cancer,” said Giles. “Some studies also suggest poorer survival rates for overweight and obese individuals.
“Despite this knowledge, we still don’t fully understand the obesity-cancer relationship. Our hope is that if we can further understand the mechanisms that underlie this relationship, we can then develop lifestyle and/or therapeutic interventions that can decrease cancer risk or improve outcomes for these patients.”
Menopause, in particular, said Giles, is a period of time when breast cancer risk is increased, especially in women who are obese. During menopause, lack of estrogen often results in the consumption of more calories, leading to weight gain. “By learning more about the mechanisms involved, we may be able to identify a window of time in which we can intervene before breast cancer develops,” she said.
“Our studies suggest that obese women might be able to lower their risk from postmenopausal breast cancer by taking measures during perimenopause to prevent weight gain and therapeutically control the metabolic effects of obesity,” she said. “These measures should include both reducing caloric intake and increasing physical activity, which is also very important.”
Research into Practice
To this end, Giles personally tries to take advantage of the outdoor activities Colorado has to offer. A varsity rower while in graduate school, she now runs, bikes, hikes and competes in triathlons. She qualified for the Boston marathon last year and is currently training to run the race in April of this year.
Moving forward, Giles also looks forward to continued research exploring the menopausal window and breast cancer risk. According to Giles, the most rewarding aspect of her research is its direct link to human health. “It’s important to me to see the findings of my studies put into practice and to result in actual health benefits,” she said.