April 26, 2010 -- Factors that increase the risk of breast cancer for white
women have less influence among women of Hispanic ethnicity, a new study
The finding comes from an analysis of population-based data on about 4,800
white and Hispanic women enrolled in a research project called the 4-Corners
Breast Cancer Study.
Known risk factors for breast cancer include reproductive history, family
history of breast cancer, menstrual history, hormone use, alcohol consumption,
physical activity, height, and body mass index.
Researchers found that:
62% to 75% of breast cancer cases among white women were attributed to
known breast cancer risk factors, compared with only 7% to 36% of cases among
Hispanic women were more likely to have characteristics associated with
lower breast cancer risk, such as earlier age at first childbirth, having more
children, shorter height, less hormone use, and less alcohol consumption.
Among premenopausal women, taller height and family history of breast
cancer were associated with increased risk in white women, but not among
Among postmenopausal women, certain breast cancer risk factors in whites,
such as recent hormone therapy and younger age at the first occurrence of
menstruation, had no or little association with breast cancer in
The researchers say the findings suggest that many of the risk factors
studied up to now explain fewer of the breast cancer cases that arise in
Hispanic women compared with white women.
"These differences are likely to contribute to disparities in breast cancer
incidence rates and could potentially reflect differences in breast cancer
development among these ethnic groups," study researcher Lisa Hines, ScD, of
the University of Colorado, says in a news release.
Ethnic differences in genetic, environmental, or lifestyle factors may
affect the susceptibility of women to the development of breast cancer.
The researchers also conclude that the study's findings indicate that the
use of models to estimate a woman's risk of breast cancer, developed from
previous research involving non-Hispanic white populations, needs to be
evaluated among other ethnic and racial populations.
Hines says that it is not fully understood why breast cancer occurs more
frequently in certain ethnic and racial groups, but that previous studies have
shown that white women have a higher incidence of breast cancer than Hispanic
Among other conclusions:
White women had a higher incidence of breast cancer compared with Hispanic
women for every age group analyzed. That difference seemed to increase with
Among premenopausal women in the group, a higher proportion of Hispanic
women than white women reported characteristics associated with a lower risk of
breast cancer, specifically, younger age at first birth, having more children,
shorter height, higher body mass index, no oral contraceptive use, and less
Characteristics associated with increased risk that were more likely to be
reported among Hispanic women included younger age at first menstruation, not
breastfeeding, and low physical activity.
Older age at first birth was the only risk factor that was associated
significantly with increased risk among both white and Hispanic women.