Diagnosing breast cancer: should you have an MRI? Magnetic resonance imaging is recommended for women at high risk, but an annual mammogram is sufficient for most
When the American Cancer Society recently issued guidelines for breast cancer screening using magnetic resonance imaging (MRI)–in addition to mammography–for women at high risk, many wondered what this recommendation meant to them. The issue was further complicated by a study in the March 29 New England Journal of Medicine that suggested women with recently diagnosed breast cancer should undergo MRI screening in the opposite breast.
“I’ve had calls from at least 100 women asking if they should have an MRI. For most, the answer is ‘no’,” says Dr. Rache Simmons, Weiscoph associate professor of surgical oncology at Iris Cantor Women’s Health Center and medical director of clinical research at Weill Medical College of Cornell University. “The mammogram is still the standard initial diagnostic test to check for breast cancer. An MRI is not necessary for women with an average risk of breast cancer.”
Are You At High Risk?
As women get older, their risk of breast cancer increases–women over 60 have a one in 26 chance (compared to a one in 229 chance for women ages 30-39).
A woman is considered at high risk for breast cancer if she has a strong family history of breast cancer (if her mother, sister, and/or daughter has a history of breast cancer, especially if they were diagnosed before age 50), has previously been diagnosed with breast cancer, or has had Hodgkin’s disease (cancer of the lymph tissues).
“For initial screening, the mammogram is still the gold standard,” says Dr. Simmons. “We still recommend that all women over age 40 have mammograms every year. If we see something that needs further evaluation, it’s very useful to add a screening ultrasound as a diagnostic test.”
Ultrasound is also appropriate for women who have especially dense breast tissue that can hide cancer. Younger women generally have denser breast tissue. “As our breasts get older, the breast tissue becomes less dense and more fatty. Fatty tissue allows the mammogram to penetrate much more easily, meaning that cancer is more easily detectable,” Dr. Simmons says.
Digital mammography, in which X-ray images are recorded in computer code instead of on X-ray film, is another option that may penetrate dense breast tissue better.
For high-risk women, adding an MRI is warranted–but it’s not without drawbacks.
“MRI can sometimes tell us more than a mammogram or ultrasound. The MRI is very sensitive, and that’s good and bad,” says Dr. Simmons. “It’s especially useful when a woman has a known diagnosis of breast cancer, because the MRI may reveal additional information that helps us determine the best treatment option.” Treatments include lumpectomy (removing a section of the breast) and mastectomy (total breast removal) and are usually accompanied by radiation, chemotherapy, and/or biologic or hormone therapy with agents such as trastuzumab (Herceptin) or tamoxifen.
However, for every cancer detected by MRI, there are many suspicious areas that, upon further testing, are revealed to be benign. “It’s very anxiety-provoking for patients to go through uncomfortable testing and end up having a negative result,” she adds. “That’s why we don’t recommend an MRI for everyone.”
Another screening test that determines whether a hereditary breast cancer (BRCA) gene mutation is present is recommended for women who have been diagnosed with breast cancer at a very young age, those with relatives diagnosed at a very young age, and women of Ashkenazi (eastern European) Jewish descent. If a woman tests positive for a BRCA mutation, she has an 80 to 85 percent risk of getting breast cancer in her lifetime. But again, Dr. Simmons says most women do not need this test. “In the general population, the chances of having the mutation are only one in 400 to 800.”
Reducing Your Risk
Smoking, high alcohol consumption, and lack of exercise all have been linked with higher breast cancer incidence. Unfortunately, the roles these factors play are fairly minor in terms of overall risk. “The frustrating thing is that women can’t do much to reduce their risk of breast cancer, because the highest risk factors, such as family history, are things you can’t change,” says Dr. Simmons. She also notes that a high-fat diet has not been associated with breast cancer, but it does increase risks for colon cancer and heart disease, so a low-fat diet is recommended for overall good health.
A GUIDE TO BREAST CANCER SCREENING TESTS
Mammogram: An X-ray of the breast that may detect abnormalities, such as tumors or tiny deposits of calcium. A digital mammogram records images on a computer rather than X-ray film.
Ultrasound: High-frequency sound waves are bounced off tissues and internal organs, producing a picture called a sonogram.
MRI: A magnet linked to a computer creates detailed pictures of areas inside the body without the use of radiation. Each MRI produces hundreds of images of the breast.
BRCA test: Blood is screened to determine if the breast cancer gene has a mutation.
WHAT YOU CAN DO
* Be vigilant about getting an annual mammogram.
* Don’t smoke.
* Limit your alcohol intake to no more than one alcoholic drink per day.
* Exercise 30 minutes a day at least five days a week.
* Ask your doctor if your family history puts you at high risk and necessitates other diagnostic tests.
ORLI R. ETINGIN, MD Editor-in-Chief
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