Does Mammography Result in Overtreatment?
June 21, 2000 -- Although the majority of women in the U.S. appear to
understand the importance of getting regular mammograms to detect breast cancer
early, most don't know enough about the common abnormalities that mammograms
can detect to make informed treatment decisions -- and their doctors should be
telling them more about them, a survey suggests.
The most common type of breast abnormality detected by mammography is ductal
carcinoma in situ (DCIS), a precancerous lesion that is confined to the milk
ducts of the breast. Many women with DCIS will never develop cancer in their
lifetime; others will, but doctors don't really know how to predict when cancer
might occur and in whom. Therefore, the management and treatment of DCIS can be
Typically, when mammography shows a DCIS-like abnormality, physicians will
do a biopsy to examine the lesion and confirm a diagnosis. Some doctors and
patients will choose the "watch and wait" method -- checking the lesion
every six months with mammography to see if it is progressing. But others will
consider aggressive treatment that may include surgery, drug treatment with
tamoxifen, or radiation.
In the June 17 issue of the British Medical Journal, researchers
suggest that if only a small proportion of DCIS lesions ever progress to
cancer, it raises questions about the possibility that many women will be
overtreated, since mammography has such a high probability of detecting
abnormalities. Co-author Steven Woloshin, MD, says the survey of 479 women that
he and colleagues conducted suggests that most women don't know enough about
DCIS to make informed decisions and that their doctors should be telling them
more about it.
"It's a very difficult dilemma, and the issue is that, in our effort to
find all cancers, inevitably we will pick up things in the 'gray' zone. For
some of these people, we don't know if we are doing more harm than good,"
says Woloshin, who is assistant professor of medicine at the VA Medical Center
in White River Junction, Vt.
But Anne Blackwood, MD, who reviewed the survey results for WebMD, says
while it is important for women to have knowledge of DCIS and other
abnormalities that can be detected on mammograms, she says fear of the
mammogram detecting something should not deter women from getting their
mammograms on time. Having a discussion about DCIS -- what it means and how
it's treated -- is something that usually happens after a diagnosis is made,
"Breast cancer is clearly an illness, and ductal carcinoma in situ is a
lesion that directly precedes invasive breast cancer," says Blackwood, who
is an assistant professor of medicine and epidemiology at the University of
Pennsylvania Cancer Center in Philadelphia. "If we can eradicate ductal
carcinoma in situ, the potential for an invasive breast cancer to develop from
that lesion doesn't exist."