Breastfeeding cuts cancer risk
2008-05-12 14:09
New York - Adult women who were breastfed
as infants may have a lower risk of developing breast cancer
than those who were not breastfed, unless they were
first-born, study findings suggest.
"As a general group, women who reported they had been
breastfed in infancy had a 17% decrease in breast
cancer risk," Hazel B Nichols, who was involved in the study, told Reuters Health.
"However, we did not observe this reduction when we looked
specifically among first-born women," said Nichols, of the
University of Wisconsin, in Madison.
A woman's age at childbirth helps predict the levels of
environmental contaminants in her breast milk, and studies have
suggested a possible link between increased breast cancer risk
and the accumulation of these contaminants, Nichols and
colleagues note in the medical journal Epidemiology.
To analyse whether an adult woman's birth order, mother's
age at the time of her birth, and whether or not she was
breast-fed alters her risk for breast cancer, the investigators
interviewed 2 016 women, aged 20 to 69 years, with breast
cancer, and 1 960 women of similar age without breast cancer.
As noted, women breastfed during infancy generally had
reduced breast cancer risk.
However, in analyses restricted to breastfed women, those
with three or more older siblings had a lesser risk for breast
cancer than first born women, the researchers found. But
breastfed women showed no altered breast cancer risk according
to their mothers' age at childbirth.
Among women who were not breastfed, reduced adult breast
cancer risk was linked with their mothers' older age at
childbirth, but the investigators identified no association
between breast cancer risk and birth order in this group.
While the current results hint that breast cancer risk may
differ according to whether or not women were breastfed during
infancy, additional studies are needed to determine if these
associations vary with duration of breastfeeding or according
to measured levels of environmental contaminants present in
breast milk, Nichols said.