100 Voices of Hope, Komen fund Ballinger’s study of role fat and muscle play in treatment

By Mary Hardin

Although oncologists have their suspicions, little is actually known about the role body composition plays in the success of cancer treatment. Indiana University breast cancer specialist Tarah Ballinger, M.D., has a theory—a theory for which she has received funding from two sources to learn more.

Ballinger has been awarded $100,000 from the IU School of Medicine’s program 100 Voices of Hope and a $5,000 Susan G. Komen Breast Cancer Challenge Grant to investigate whether patients with less muscle or more fat have worse treatment outcomes.

Typically, body mass index, or BMI, is the scale used to determine whether a patient is obese or not. However, as Ballinger stressed, BMI does not tell the whole story. “Obesity as defined by BMI has been associated with worse survival in women with breast cancer, but that number can be misleading,” she said.

For instance, a body builder weighing 220 pounds would have a much greater percentage of muscle mass than a sedentary person also weighing 220 pounds. However, both may have the same BMI. 

“Typically, we think of obesity as someone’s BMI, but people can have the same BMI and the actual composition of their body is very different in terms of how much muscle or fat they have. Muscle and fat are endocrine organs that influence a person’s metabolic profile. If a tumor is living inside a person, there are a lot of things about that person that might influence how that tumor grows,” said Ballinger, assistant professor of clinical medicine at IU School of Medicine and a member of the IU Simon Cancer Center.

Ballinger will review a breast cancer clinical trial from the Eastern Cooperative Oncology Group (ECOG), of which the IU Simon Cancer Center is a member, that enrolled 600 women with estrogen positive stage IV breast cancer. Using abdominal CT scans, Ballinger will quantify the amount of skeletal muscle, adipose (fat) tissue, and the amount of fat that is infiltrating muscle tissue and compare that with the outcomes of each patient. Survival, response to treatment, side effects and quality of life will all be scrutinized.

Ballinger predicts that muscle mass will be found to play a positive role in the treatment outcome of these breast cancer patients.

“I suspect that muscle mass is more predictive than body weight in terms of how patients will respond to treatment,” Ballinger said. “People with less muscle, or poorer quality muscle, will do worse and patients who are both obese and have low muscle mass will not respond as well to treatment.”

If correct, Ballinger said physicians might rely less on BMI and more on actual body composition to make decisions about treatment for women with estrogen positive breast cancer.

“The results may suggest mechanisms of drug resistance and efficacy based on body composition and may lead physicians to suggest other interventions for patients who have less muscle or more body fat,” Ballinger said.

Started by a patient-advocate, Mary Beth Gadus, 100 Voices of Hope is a unique partnership between community members and researchers. Each year, the program raises money at IU School of Medicine for the IU Simon Cancer Center and the Vera Bradley Foundation Center for Breast Cancer Research, providing $100,000 awards for pilot projects in metastatic breast cancer research. Since 2008, $1.7 million has been raised, funding 19 research projects and 18 different researchers.

Each year, Susan G. Komen awards three Breast Cancer Challenge Grants to researchers interested in links between obesity and cancer during the Obesity Society’s annual national conference. Ballinger received the honor during the 2018 conference and will present her findings at the 2019 summit in Las Vegas.