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.
Sexton found that obesity is not associated with breast
cancer risk at any age for Mexican-American women. And unexpectedly found that
gaining weight during adulthood reduces breast cancer risk.
"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.