When Should Women Have MRI Scans After Mammograms?
Mammograms or MRIs - which is best for detecting breast cancer early?
That's the question facing millions of women who are unsure of which screening method is best, says Dr. Adele Lipari, breast imaging section chief at the James Cancer Hospital and Solove Research Institute at Ohio State University.
The answer is simple, says Lipari, who also is an assistant professor of clinical radiology at Ohio State: "All women need mammograms, and only certain women need an MRI. Physicians must tailor the type of screening for each patient based on her risk factors."
Breast cancer is the second leading cause of cancer-related death in women. This year alone, about 178,000 women will be diagnosed with breast cancer and 40,000 will die of the disease, according to the American Cancer Society.
Mammography screening and advances in breast imaging have lowered the death rate from breast cancer in recent years. The improved methods of early detection include MRI (magnetic resonance imaging) and digital mammography. Traditional or analog mammograms, also known as film-screen, are also still widely available.
Yet the various breast cancer screening choices available may be somewhat confusing for women, Lipari says. Earlier this year, the American College of Radiology Imaging Network released the results of a major multicenter study of almost 50,000 women that compared digital and analog mammography, and also explored MRI use.
The study, referred to as DMIST (Digital Mammographic Imaging Screening Trials), which included patients at The James, found that the diagnostic accuracy of analog vs. digital mammography is similar except in certain subsets of women.
Digital mammography was found to detect up to 28 percent more cancers in premenopausal and perimenopausal women, and in women under age 50 who have dense breast tissue.
Digital mammograms uses X-rays to produce electronic images of the breast that are stored on a computer. The same digital technology used for digital cameras is used for these mammograms, giving radiologists another powerful tool to detect breast cancer.
"Digital mammograms are easy to manipulate," says Lipari. "We can darken or lighten the image, or zoom in on calcifications and other masses. Digital mammograms are especially valuable for younger patients with dense breasts, as breast cancer can be difficult to detect - and is often more aggressive - in these patients."
Traditional mammograms, or analog mammograms, are also a good method for detecting breast cancer, especially in women with less-dense breasts.
"Whether it's analog or digital mammography, mammograms do save lives. Having one is more important than which kind you have," says Lipari.
According to the DMIST study, annual MRI scans are recommended for women with a greater than 20 percent lifetime risk of developing breast cancer.
These individuals include those with a BRCA1 or BRCA2 gene mutation; those with a first-degree relative having one of those mutations; those with a strong family history of breast or ovarian cancer; and women who had undergone chest radiation between the ages of 10 and 30.
"The recommendation was limited to this subset of women because of the increased cost of MRI and the higher number of false positive results," Lipari says. "More studies are needed to learn if other high-risk women may benefit from annual MRI screenings."
The DMIST study also found that MRI scans may help identify breast cancer in the opposite breast of women diagnosed with the disease. Up to 10 percent of women with breast cancer develop a tumor in the opposite breast.
"Clearly, MRI scans are an option for high-risk patients or those with appropriate risk factors, but the exam is still not considered a substitute for a mammogram," Lipari says.