Breastfeeding can reduce the risk of breast cancer for women who
have their first childbirth after the age of 25, according to a study presented
at a news conference on Monday April 16 at the 2007 annual meeting of the
American Association for Cancer Research held in
Los Angeles.
The study led by researchers at the
University of
Southern California
suggests that breastfeeding can offset the increased risk of breast cancer in
women associated with their late childbirth.
“Breastfeeding may have a protective effect that negates the
increased risk of breast cancer associated with late pregnancies,” says Giske
Ursin, M.D., Ph.D, associate professor of preventive medicine at the Keck
School of Medicine of the
University
of
Southern California.
“As more women may choose to delay pregnancy until after 25,
it is important to note that breastfeeding provides protection against both
estrogen and progesterone receptor positive and negative tumors.”
Having a first full-term pregnancy before the age of 25 and
having many children protect only against the type of breast cancers that
express estrogen and progesterone receptors. The factors do not have an effect
on rare tumors that do not have the noted receptors. Breastfeeding, however,
appears to protect against both types of breast tumors, Ursin says.
The researchers came to the conclusion after analyzing data
for women aged 55 and older who participated in the Women’s Contraceptive and
Reproductive Experiences (CARE) Study including 995 invasive breast cancer
patients.
The researchers analyzed the associations among their age at
first birth, their breastfeeding history and hormone receptor status.
Previous results from the Women’s CARE Study have already
shown that women with their first pregnancy occurring at an age younger than 25
and having many children (four or more pregnancies) have a reduced risk of
breast cancer, Ursin says.
The new study found that breastfeeding appears to have a
protective effect against breast cancer regardless of the age at which women had
their first pregnancy, Ursin says.
Having many children can only protect those who had their
first pregnancy before the age of 25 years.
First birth often given after the age of 25 in
the
United States
is linked with an increased risk of hormone receptor negative breast cancer.
“Evidence suggests that women who have children after age 25
can reduce their risk of breast cancer by choosing to breastfeed,” Ursin says.
