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Washington, D.C. — Preliminary results of a research study at Lombardi Cancer Center
indicate that newly diagnosed breast cancer patients with a strong family
history of this disease are more likely to take more aggressive steps to
eradicate their cancer if genetic testing shows they have the inherited
form of the disease.
Only
a small percentage of women with breast cancer have the inherited form,
which means that they have mutations in the BRCA1 and BRCA2 breast-cancer
genes (and perhaps other genes which have not yet been identified). Women
with a hereditary predisposition to breast cancer run a higher risk of
developing not only second breast cancers, but also a higher risk of ovarian
cancer. However, for most women, breast cancer is caused not by genetic mutations, but rather by other factors.
The
National Cancer Institute-sponsored study was designed to assess whether
women thought to have hereditary breast cancer would be interested in free-of-charge
genetic testing and counseling, and whether the results of the test would
change their minds about how to proceed with treatment. The study involved
175 recently diagnosed women whose breast cancer was suspected of being hereditary.
“Although
we are still recruiting for this study and can’t draw any definitive conclusions
at this point, we are definitely seeing some interesting trends,” said
Claudine Isaacs, MD, associate professor of hematology/oncology. “Our findings
so far indicate that newly diagnosed breast-cancer patients at high genetic
risk for breast cancer are likely to want genetic counseling and testing,
and that the results of this testing have an impact on how women make their decision about whether to have surgery, such as bilateral mastectomy.”
About
70 percent of the eligible women chose to have the testing, Isaacs said,
adding that those women were more likely to undergo mastectomies than women
who declined the genetic testing altogether. Forty-three percent of the
women in whom genetic testing uncovered a hereditary breast-cancer risk
opted to have a bilateral mastectomy. Of the women who were tested but
received negative or inconclusive results, 24 percent decided to have a
bilateral mastectomy, and only 4 percent of the women who declined testing altogether chose the bilateral mastectomy option.
Of
the 70 percent who underwent the genetic testing, 21 women had positive
results, meaning that they had the genetic mutations indicative of heightened
risk for second breast cancer and ovarian cancer. Twelve of these women
had been planning to have only a lumpectomy before they received the results
of the genetic testing. After getting the positive result, eight proceeded
as planned, while four changed their minds and had a bilateral mastectomy
instead of the breast-conserving procedure they had originally planned.
Three of the 21 had originally planned to have a unilateral mastectomy
(only one breast removed)—but after receiving the positive results, all
three changed their minds, and one had a lumpectomy while the other two underwent a bilateral mastectomy.
Also
collaborating on this research were Marc Schwartz, PhD, assistant professor
of cancer control research; and Caryn Lerman, PhD, professor and associate director of cancer control and population science.
The
continuing study also will focus on analysis of various subgroups—for example,
what factors, if any, predict which women will be interested in pursuing
counseling and testing, the impact of genetic counseling and testing on
women’s psychosocial well-being, and whether the extent of family history
in women with uninformative or negative test results influences the choices they make.
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