TUESDAY, Sept. 14, 2004 (HealthDayNews) -- Magnetic resonance imaging (MRI) is more effective than other screening methods for finding breast cancer in women whose genes leave them susceptible to the disease.
Among women with the BRCA1 or BRCA2 genetic mutations, MRI was found to be superior to mammography, ultrasound, or a clinical breast exam in detecting tumors, according to a study appearing in the Sept. 15 issue of the Journal of the American Medical Association.
If a woman at a higher risk of breast cancer due to these mutations has access to breast MRI, she should consider it, said Dr. Ellen Warner, a medical oncologist at Toronto-Sunnybrook Regional Cancer Centre in Toronto and the study's lead author.
But the caveat, she added, is that a women who decides to undergo a screening MRI should "realize there is a high incidences of false positives," Warner said. "The first year, 9 percent [of those who get a screening MRI] are biopsied and turn out to be nothing." The number of false positives drops after that, she said.
In the study, Warner and her colleagues evaluated 236 women ages 25 to 65 who had either the BRCA1 or BRCA2 mutations. Women who are genetically predisposed to breast cancer because of these mutations often decide to have prophylactic mastectomies. But if they do not, they have a lifetime risk of breast cancer of up to 85 percent, according to Warner.
The women in the study had mammography, MRI, ultrasound, and clinical breast exams and underwent one to three annual screenings. During the period of the study, from November 1997 through March 2003, 22 breast cancers were detected. Of these, 77 percent were detected by MRI, vs. 36 percent by mammography, 33 percent by ultrasound, and 9.1 percent by breast exam. When combined, all four screening methods had a sensitivity of 95 percent, vs. just 45 percent for mammography and clinical exam combined.
Warner and her team concluded that MRI screening is likely to become the "cornerstone" of screening for women with mutations. "It looks very promising," Warner said. But first, more study is needed to evaluate the effect of MRI not just on detection of breast cancer, but on survival, Warner said.
"If we follow up and show that MRI reduced death, it will become the mainstay for screening for mutation carriers," Warner said.
Since about 1995, Warner said, "researchers have been looking at the value of MRI to screen those with the mutation." However, she added, "It's still considered investigational because we don't know if it will affect survival."
In an editorial accompanying the study, Drs. Mark E. Robson, assistant attending physician at Memorial Sloan-Kettering Cancer Center in New York City and his co-author, Dr. Kenneth Offit, write that the study results "clearly affirm that MRI is significantly more sensitive than mammography in detecting breast cancer in women at hereditary risk," but caution that several questions remain.
They, too, said that the better sensitivity of MRI may or may not translate to a reduction in deaths from breast cancer in these women.
And, like Warner, they said that MRI screening should not be considered at this time for women at lesser degrees of risk, such as those who don't carry the genetic mutation.
In an interview, Robson stressed that women with genetic mutations who wish to have an MRI find someone who is experienced at doing these tests. The best way to find experienced operators, he said, is to go to a major university center, a cancer center, or a community cancer center.
More information
To learn more about breast screening methods, visit the American Cancer Society.
