Postpartum obesity can lead to breast cancer, study finds

November 6, 2014

Though it has long been thought that pregnancy can reduce the chance of breast cancer, a new study finds this may not be so, at least for a specific type of breast cancer.

Dr. Liza Makowski

The study, led by Liza Makowski, PhD, assistant professor of nutrition at The University of North Carolina at Chapel Hill’s Gillings School of Global Public Health, found that pregnancy can increase the risk of basal-like breast cancer, a triple-negative subtype of breast cancer.

Titled “Obesity-mediated regulation of HGF/c-Met is associated with reduced basal-like breast cancer latency in parous mice,” and published online Oct. 29 in PLOS One,  the study used unique mice that present with cancers resembling human basal-like breast cancer.

“We also found that in mice that became obese during the postpartum period, the tumors for this type of cancer became extremely aggressive,” Makowski said. “This is significant because this is a type of breast cancer that does not currently have any specific drug therapies.”

Sneha Sundaram, PhD, postdoctoral research associate in the Gillings School’s Department of Nutrition and lead author on the manuscript, found that obesity increased a certain receptor called c-Met for a growth factor that has been shown to cause cancer.

“We are currently investigating drugs to block this growth factor in our obese mice,” Sundaram said.

Makowski cautioned that because the study was conducted with mice, the results are not definitive. They do, however, offer cause for concern.

The risk could be greatly mitigated by two key factors, she said – keeping a healthy weight and breastfeeding.

“This is good news because both tend to be within the mothers’ own control,” she said. “Basal-like breast cancer is affected by lifestyle choices. Maintaining a healthy weight and breastfeeding are important actions to help reduce risk.”

Co-authors from the Gillings School include Melissa Troester, PhD, associate professor of epidemiology, and Alex Freemerman, PhD, research associate in nutrition. Co-authors from the UNC School of Medicine are Joe Galanko, PhD, research assistant professor in medicine gastroenterology, and Kirk McNaughton, MS, research analyst in cell biology and physiology. Other co-authors are Kat Bendt, MS, and David Darr, MS, both research associates at the UNC Lineberger Comprehensive Cancer Center’s Mouse Phase 1 Phenotyping Unit.

The full paper can be found online.