5 June 2003
Cancer in Some Women Is Tied to Early Start of Puberty
study of twins suggests early puberty may trigger breast cancer
in women who are already at unusually high risk because of their
women's risk of breast cancer is believed to be linked to her lifelong
exposure to the sex hormone estrogen, with slight increases for
those who start menstruating early, reach menopause late, never
have children or have them late. However, the new study suggests
that going through puberty early may be especially ominous for some
women genetically predisposed to get the disease, the rush of hormones
at puberty alone -- rather than long-term exposure -- may result
in breast cancer later in life, according to the study from the
University of Southern California in Los Angeles.
a lot we don't know about the causes of breast cancer, but what
we need to know ... is where to look," said researcher Ann
S. Hamilton. "This provides some more clues about a different
approach in looking for genetic factors."
findings appear in Thursday's New England Journal of Medicine.
study looked at 1,811 sets of identical and fraternal female twins.
In each set, one or both twins had breast cancer. The researchers
asked about their age at puberty and menopause, pregnancies and
other risk factors and looked for patterns.
thing stood out: For identical twins with cancer, the first twin
to reach puberty was five times as likely to get the disease first.
The link was even stronger when menstruation began early, before
the age of 12. Other factors -- a later age at menopause, fewer
children and a later first pregnancy -- made no difference.
identical twins share genes, the researchers assume there was a
hereditary reason behind the vulnerability to the onset of hormones.
Scientists so far have discovered a few gene mutations that increase
the risk of breast cancer.
Hartge of the National Cancer Institute, who wrote an accompanying
editorial, said the study was provocative but its conclusions would
have to be repeated in other studies. The study was partly funded
by the institute.
we begin to understand how the hormone and gene go together to later
increase the risk of breast cancer ... we probably could figure
out how to intervene," she said.
Manson of Harvard's Brigham and Women's Hospital said the implications
of the study are worrisome given the gradual decline in the age
of puberty in the U.S. and the rise in childhood obesity. Body fat
can stimulate hormones. If the findings are correct, "There's
even more impetus to try to reverse this epidemic of obesity in
children," Dr. Manson said.