Study: No link between breast cancer, banned chemicals
October 29, 1997
Web posted at: 9:34 p.m. EST (0234 GMT)
BOSTON (CNN) -- Two banned chemical compounds suspected of
increasing a woman's risk of developing breast cancer do not
appear to have any direct correlation to the disease,
according to the results of a new study.
In the study, published in Thursday's edition of the New
England Journal of Medicine, researchers from the Harvard
School of Medicine and Brigham and Women's Hospital tested
the blood of two groups of women, looking for evidence of
exposure to the pesticide DDT and PCBs, a class of industrial
Both substances were banned two decades ago but were so
widely used that traces remain in the environment.
One group of 240 women had developed breast cancer; a second
control group of 236 had not.
"We did not find that these chemicals were associated with
increased risk of breast cancer," said Dr. David Hunter, who
led the study. "We found that the levels of these chemicals
were actually somewhat lower in the women who went on to get
breast cancer versus the women who did not."
Several previous studies had indicated that there might be a
link between these two compounds and breast cancer because
the chemicals mimic the female hormone estrogen, which has
been linked to the disease.
However, Barbara Brenner, a breast cancer survivor and
advocate for increased awareness and research, says this
study does not let the environment off the hook.
"I have no doubt that there are things in the environment to
blame," Brenner said. "I don't know what they are, and nobody
else does either."
Breast cancer affects more women than any other type of
cancer, and the rate of occurrence has increased by an
average of 1 percent a year over the past 57 years. Yet no
one knows for sure what causes it or why it seems to be
In an editorial accompanying the study, Dr. Stephen H. Safe
of Texas A&M University said the results should reassure the
public that these chemicals don't cause breast cancer. He
noted that the disease has increased over the past 20 years,
at the same time that the chemicals have been banned.
"It is incumbent on scientists, the media, legislators and
regulators to distinguish between scientific evidence and
hypotheses and not to allow a 'paparazzi science' approach to
these problems," Safe said.
Medical Correspondent Al Hinman and Reuters contributed to