Krystal Sexton, Ph.D., talked to Time Magazine about her research last Friday morning, then reviewed it again for a room full of colleagues, friends and family that afternoon to complete the final step for her doctorate.
Monday, her results were displayed on a poster at the annual American Association for Cancer Research Frontiers in Prevention meeting in Philadelphia.
"Obviously, we aren't recommending that women go out and gain weight," Sexton said. "These results are preliminary and need to be validated in a larger study. Obesity remains a risk factor for cardiovascular disease."
Sexton studied 148 Mexican-American women who had breast cancer and 330 in a control group who did not have it. "We found that risk fell by 8 percent for every 5 kilograms (11 pounds) gained," Sexton said. Weight was analyzed at ages 15, 30 and at diagnosis or an equivalent age in controls.
One hypothesis for the risk reduction: Women who are overweight or obese enter menopause earlier, which reduces their lifetime exposure to estrogen, thus decreasing their cancer risk. Women who did not have breast cancer in Sexton's study entered menopause two years earlier.
Her study highlights an important point, that you can't study one population group and assume that the findings apply to others. Most previous research showed that obesity reduces breast cancer risk for premenopausal women and increases risk for post-menopausal women, but focused on non-Hispanic white women almost exclusively.A massive literature search by Sexton turned up hundreds of studies of white women, but only a handful that looked at Mexican-American or African-American women.
Sexton said her career will be devoted to understanding such health disparities. She will continue the breast cancer study as a postdoctoral fellow working with Melissa Bondy, Ph.D., professor in MD Anderson's Department of Epidemiology in the Division of Cancer Prevention and Population Science.
She conducted her research with Bondy as a Susan G. Komen fellow in breast cancer disparities research at The University of Texas Health Science Center at Houston (UTHealth) School of Public Health.