THURSDAY, Aug. 15 (HealthDay News) -- Breast-feeding for more
than six months appears to guard nonsmoking women against breast
cancer for longer periods of time, a new study suggests.
Smoking canceled the benefits of breast-feeding, but there was a
decade of difference in diagnosis among nonsmoking breast cancer
patients, depending on how long they breast-fed, the researchers
Nonsmokers who didn't breast-feed or did so for less than three
months were diagnosed at an average age of 58, while women who
didn't smoke and breast-fed longer than six months were diagnosed
at an average age of 68. Those who breast-fed longer than six
months but also smoked were diagnosed at an average age of 47.
"Those women diagnosed with breast cancer who did not smoke and breast-fed for longer than six months were diagnosed much later -- an average of 10 years later," said study author Emilio Gonzalez-Jimenez, a researcher at the University of Granada in Spain.
Although much research has linked pregnancy and a reduced risk
of breast cancer, studies on the protective effects of
breast-feeding have produced conflicting results, Gonzalez-Jimenez
His team looked at the medical records of more than 500 women,
aged 19 to 91, who had been diagnosed and treated for breast cancer
from 2004 through 2009 at a university hospital in Granada.
The researchers found an association between breast-feeding and
age at cancer diagnosis, but they did not prove a cause-and-effect
link. The association held, however, even when they factored in a
family history of cancer. Other research has linked smoking with
The new study is published online Aug. 15 in the
Journal of Clinical Nursing.
The study, however, is relatively small, said Debbie Saslow,
director of breast and gynecologic cancer for the American Cancer
Society. For example, only 26 nonsmoking women in the study
breast-fed for more than six months.
Previous research, including a review of dozens of studies, has
produced very mixed findings, she added, and this latest finding is
"The jury is still out," Saslow said. "There have been many studies showing breast-feeding is slightly protective [against breast cancer], but that the effect is small and it's more protective the longer you breast-feed."
In one review, the risk of breast cancer declined by about 4
percent for each 12 months of breast-feeding, whether it was done
with one child or several, she said.
The American Cancer Society expects more than 234,000 cases of
breast cancer to be diagnosed in 2013. About 40,000 deaths are
expected this year.
According to the U.S. Centers for Disease Control and
Prevention, as many as 77 percent of U.S. infants are breast-fed as
newborns. Of infants born in 2010, however, just 49 percent were
still breast-feeding at six months and only 27 percent were doing
so at 12 months.
"There are various explanations why breast-feeding seems to prevent breast cancer," Gonzalez-Jimenez said. "The most probable of these are the hormonal changes that take place during pregnancy and lactation."
Among those changes are reduced levels of estrogen, which fuel
many breast cancers, and physical changes in breast cells.
"I recommend breast-feeding for longer than six months," Gonzalez-Jimenez said. Not smoking is his other piece of advice.
To learn more about risk factors for breast cancer, visit the
American Cancer Society.
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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