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Jun. 27--High-risk women who rely on mammograms as a weapon against breast cancer may actually increase their chances of getting the disease, according to preliminary research released Monday.
The study looked at 1,600 European women with genetic mutations that predispose them to get breast cancer. Women who reported having had at least one chest X-ray were 54 percent more likely to develop breast cancer than those who had never had one.
This Catch-22, reported in the July 20 issue of the Journal of Clinical Oncology, means women with mutations in BRCA1 or BRCA2 genes might want to consider being screened with magnetic resonance imaging instead of X-rays, doctors said.
It also suggests that women and men with a family history of breast or ovarian cancer might want to consider genetic testing to find out if they carry a mutation before they get any X-rays to the chest area, doctors said.
Exposure to high doses of ionizing radiation--such as from nuclear fallout--is known to cause breast cancer. But the risk is small enough for the vast majority of women over 40 that experts still recommend annual screening with mammograms, which emit much lower doses.
In women under 40, mammograms are less accurate and the radiation is potentially more dangerous. But hereditary breast cancer often strikes women under 40.
"Maybe after age 30 the risk of cancer is high enough to justify the potential long-term risk of cumulative radiation," said Dr. Olufumilayo Olopade, director of the cancer risk clinic at the University of Chicago Medical Center. "So we traditionally recommend that high-risk women--especially mutation carriers--start screening with mammography at 25.
"This [study] calls into question, is it possible by starting so young we might increase their risk?"
MRI could eventually become the preferred screening tool for high-risk women, said Olopade, who wrote an editorial accompanying the study. But it's not a perfect solution.
MRI alone can be hard to read and have a high rate of false-positive results, which lead to unnecessary biopsies, said Dr. Virginia Kaklamani, an expert in breast cancer and cancer genetics at Northwestern University.
So, if a radiologist found something suspicious on an MRI, she said, "I'd probably recommend a mammogram" despite the radiation exposure.
"Until we have more research," Kaklamani said, "younger women with a genetic susceptibility to breast cancer are between a rock and a hard place."
David Goldgar, a genetic epidemiologist at the University of Utah and lead author of the study, said it is too soon to draw conclusions about who should or should not have screening mammograms. He said further research was needed to confirm the results.
The study "is not enough to mandate changes in clinical practice," said Dr. Kathy Albain, director of the breast research program at Loyola University Medical Center in Maywood. "But I think it's enough to modulate our recommendations for certain patients.
"If you have very young patients who are also BRCA carriers, maybe you don't send them for a chest X-ray at the first cough," she said.
Kaklamani said women known to be mutation carriers might also think twice about getting mammograms before age 35.
The European study did not look at breast X-rays, but the radiation exposure with a mammogram is significantly higher than that with a standard chest X-ray.
The researchers hypothesized that radiation might be very risky for BRCA mutation carriers because those genes are believed responsible for repairing DNA damage. Defective genes would be less able to repair radiation damage.
Dr. Lydia Usha, who runs the RISC (Rush Inherited Susceptibility to Cancer) Center at Rush University Medical Center, said more high-risk women might decide to have prophylactic mastectomies--surgical removal of both breasts--if the study results are confirmed. Most patients don't choose that option now.
Maria Pradd, 38, is one of Kaklamani's patients. A former sales training and development manager, Pradd was diagnosed with breast cancer in 2004. Only after having a lump removed and undergoing treatment did she discover she had a BRCA1 mutation.
Pradd said she will consider having her ovaries removed after she has children, to reduce her risk of getting both ovarian and breast cancer. But she is not interested in prophylactic mastectomy.
She's philosophical about risk, and about how far she's willing to go to reduce it. "I know my chances of having another cancer are greater now," said Pradd. "But I could also walk across the street and get hit by a bus."
She said she would like to add an annual MRI to her screening regimen, but her insurance carrier so far has balked. A breast MRI can cost between $1,000 and $3,000. Mammograms are about a tenth of that.
The odds of having one of the known breast cancer genes is about 1 in 800 in the general population, said Usha. But it can be much higher in certain ethnic groups, such as the 1 in 40 figure for Ashkenazi Jews, or Jews of Eastern European origin.
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Women with genetic mutations predisposing them to breast cancer are even more likely to develop the disease if they have had at least one chest X-ray, the study suggests.
1 in 800
Estimated number of people with one of the genetic mutations
1 in 40
Ashkenazi Jews estimated to have one of these genetic mutations
54%
Increased likelihood that individuals who have a genetic mutation and have had chest X-rays will develop breast cancer
WHO SHOULD GET TESTED
Anyone with a family history of breast or ovarian cancer, especially in a male or premenopausal female relative.
WHERE TO LEARN MORE
- American Society of Clinical Oncology's People Living With Cancer Web site: www.plwc.org
- National Cancer Institute Web site: www.cancer.gov/cancertopics/screening/breast
Source: Journal of Clinical Oncology
jperes@tribune.com
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Copyright (c) 2006, Chicago Tribune
Distributed by Knight Ridder/Tribune Business News.
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