Breast cancer awareness is
at an all time high. Awareness campaigns have mushroomed
in recent years creating a nation obsessed with breast
self-exams and routine mammography. In our fervour to
detect malignant disease we've also increased detection
of benign breast lesions. While it's better than discovering
that your patient has breast cancer, what does a diagnosis
of benign disease really mean? "This is such a common
condition," said Dr Lynn Hartmann, an oncologist at the
Mayo Clinic College of Medicine in Rochester, Minnesota,
"and what has been out there most commonly is that women
with benign breast disease have an increased risk of breast
cancer, at about a relative risk of 1.5."
Dr Hartmann's research, published
in the July 21 edition of The New England Journal
of Medicine aimed to put this risk into perspective.
"We have a large enough population here, let's look
at subsets and really see what's driving that 1.5 relative
risk. Clearly it's coming from some women who do have
a significant increase, and it's carrying along many
women whose risk is not increased," she said.
STRENGTH IN NUMBERS
The study boasts a participant
population that's 12,132 women strong. The women, aged
18-85, were diagnosed with benign breast disease on
biopsy between 1967 and 1991. The researchers also acquired
biopsy tissues and complete followup data for a median
of 15 years for 9,087 subjects. The researchers were
then able to tease out the differences between the common
sub-types of benign disease and determine the increase
in breast cancer risk associated with family history.
At their initial biopsy, two-thirds
of the women had non-proliferative lesions, while those
with proliferation without atypia made up 30%, and the
remaining 4% had atypical hyperplasia. To date, 707
have developed cancer, 254 more than expected for the
general population (a relative risk of 1.56).
The cancer risk was as expected,
but this risk was not evenly distributed. "Reports have
said that if a woman has both atypia and a significant
family history that her risk is increased, say 10 times.
We did not see that, and I think we have the tightest
confidence intervals on that atypia and family history
question that exists in the literature right now," asserted
Dr Hartmann. "The degree of family history was an independent
risk factor," noted the authors. Women with non-proliferative
findings and no family history showed no increased risk.
In contrast, proliferative disease without atypia increased
relative risk to 1.88. But it is the presence of atypia
that clearly increases risk, conferring a 4.24 relative
risk generally and a seven-fold increase in risk if
found before age 45.
While the findings may allow many
patients with benign disease to rest easy, Dr Hartmann
advised, "when [atypia] is found, albeit uncommonly,
that certainly indicates a woman at high risk...[she]
should be referred to a breast centre at least for consideration
of trials of chemoprevention or better surveillance.
In the intermediate group, the women that have some
proliferative change and roughly a doubling of their
risk, we would not identify them as needing special
intervention."
NEJM July 21, 2005;353(3):229-37
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