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Test May Help Spot Some Breast Cancer
May 23, 2006 -- In some women whose genes put them at high risk of breast cancer, getting annual magnetic resonance imaging (MRI) along with mammography may be cost-effective.
So says a study in The Journal of the American Medical Association. The study relies on a computer model, not actual patients.
The researchers included Sylvia Plevritis, PhD, of Stanford University’s radiology department. She and her colleagues based the computer model on an imaginary group of 25-year-old women born in 1980 with mutations in their BRCA1 and/or BRCA2 genes.
Such mutations are tied to a 45% to 65% increase in a woman’s risk of developing breast cancer at some point in her life, according to background information in the study. BRCA1 and BRCA2 gene mutations are also tied to a higher risk of ovarian cancer.
According to the Susan G. Komen Breast Cancer Foundation, inherited gene mutations account for only about 5% to 10% of all breast cancer cases.
Screening Methods
Currently, annual mammograms are recommended for women with BRCA 1 or BRCA2 genes, starting at age 25, write the researchers.
While mammography is often helpful at spotting breast cancer, it’s not a perfect test. Dense breast tissue, which is common among young women, may make it harder to spot tiny breast cancers on mammograms.
“Although breast MRI screening is highly sensitive, it increases the rate of false-positive results, and it has not been shown to reduce breast cancer mortality,” write Plevritis and colleagues. They also note that MRI is about 10 times as expensive as mammography.
Some women with the BRCA1 and/or BRCA2 genes opt to have their breasts removed (mastectomy) or take drugs such as tamoxifen as preventive measures. Others prefer to follow screening guidelines, coping with breast cancer if and when it happens.
Computer Model
Plevritis and colleagues designed a computer model that calculated the cost-effectiveness of three approaches, used over a lifetime, for 25-year-old women with BRCA1 and/or BRCA2 genes.
Those three approaches were no screening, annual mammography from age 25-69 years, or annual mammography from ages 25-69 years plus annual MRI for specific age groups.
The researchers assumed the imaginary women hadn’t had breast cancerbefore age 25 and hadn’t had their breasts or ovaries removed or taken drugs to prevent breast cancer.
The researchers also made certain assumptions about the accuracy of mammography and MRI, such as the size of tumors each test could detect. They also assumed that if breast cancer was detected, the women would get the affected breast totally removed (mastectomy) and possibly the other breast, too.
Data came from a large U.S. cancer database and from Medicare payments from 2005.
Benefits With Dense Breasts
The computer model showed that annual MRI plus mammography was cost-effective for women aged 35-54 years “for whom conventional mammography is insensitive due to breast density,” write Plevritis and colleagues.
Annual MRI plus mammography wasn’t cost-effective for women younger than 35 -- in whom breast cancer is rarer -- or in women 55 and older, who have shorter life expectancy and may have other health problems, the study shows.
“Screening BRCA1 and BRCA2 mutation carriers for breast cancer with MRI added to mammography can be cost-effective at selected ages even though MRI is expensive and increases the number of false positive findings,” the researchers write.
They add that MRI’s cost effectiveness rises as mammography’s accuracy dips and as the results affect patients’ quality of life. Digital mammography and other improvements in mammography could shift the results, the researchers note.
Remember, the findings aren’t based on actual people. The study doesn’t include direct advice for women with the BRCA1 and/or BRCA2 gene mutations.
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October is National Breast Cancer Awareness Month, and a new study reveals why a high number of women with the disease still prefer to have the entire breast surgically removed instead of just the tumor. It's not always because doctors recommend it.
