Mammography Plus MRI Spots More Breast Cancer
Mammography coupled with contrast-enhanced magnetic resonance imaging (MRI), conducted on an annual basis, would catch almost all tumors in women at high risk for breast cancer, according to a study reported in The Lancet.
The findings echo the results of two smaller studies, one Canadian and one Dutch, that were reported in the past year.
"This is essentially a slam dunk in terms of affirmation of the MRI," says Dr. Jeffrey Weitzel, director of the clinical cancer genetics department at City of Hope Cancer Center in Duarte, Calif.
"This is another confirmatory paper demonstrating superiority of MRI over mammography," adds Weitzel, who was not involved with the research. "We would use both as complementary techniques."
Women at high risk for breast cancer because of an inherited susceptibility represent about one percent of all women with the disease, according to a Lancet editorial that accompanied the article.
Some women in this group elect to have prophylactic mastectomies, which have been shown to almost eliminate the risk of developing breast cancer. Others elect close watching. For the latter strategy to be effective, however, the tumors need to be caught early, when they can still be cured.
In general, women who have a strong family history of breast cancer, as well as women who have proven BRCA1 or BRCA2 gene mutations, are more likely to develop tumors at a young age, when their breast tissue is more dense.
Mammograms, which are x-ray examinations of the breasts, are the standard of care for women aged 40 and over, but are less effective when tissue is dense.
Breast contrast-enhanced MRI, on the other hand, has a higher likelihood of detecting malignancies even when the breast tissue is dense. MRI is a diagnostic procedure that uses a combination of a large magnet, radiofrequencies, and a computer to produce detailed images of organs and structures within the body.
The new research involved 649 women from 22 radiology and genetic centers throughout the United Kingdom who were between the ages of 35 and 49.
All were considered at high risk for breast cancer either because of a family history or because they had a proven genetic mutation.
Each participant was given an annual MRI and mammography for two to seven years.
Sensitivity, which refers to the probability of having a positive test when a tumor actually exists, was almost twice as high (77 percent) with the MRI compared to mammography (40 percent).
However, it was 94 percent when both methods were used together.
Specificity, which refers to the probability of a negative test when the patient is in fact cancer-free, was 93 percent for mammography, 81 percent for MRI, and 77 percent with both methods.
Contrast-enhanced MRI was particularly effective among carriers of the BRCA1 gene, detecting 92 percent of tumors while mammography only picked up 23 percent.
The high sensitivity means women can have more confidence in negative results, Dr. Weitzel points out.
Mammography, on the other hand, was better at detecting ductal carcinoma in situ (DCIS) or early, noninvasive cancer.
"The MRI has a blind spot for DCIS, but mammography is pretty good, so you can cross-reference," Dr. Weitzel notes.
Also encouraging was the fact that the tumors that were found tended to be small, and to not have advanced to the lymph nodes.
The study did not look at whether the combination of MRI and mammography impacted survival rates.
There are also questions that will affect how the combination could be implemented in actual practice.
For one thing, cost may be a factor. While mammography is fairly inexpensive, breast MRIs can run about $1,000 per breast, Dr. Weitzel says.
Dr. Weitzel also cautions women not to neglect having an annual clinical breast examination performed by their physician.
In addition, women over the age of 20 should perform monthly breast self-examination (BSE). BSE should not be used in place of, but in addition to, clinical breast examination and mammography.
Always consult your physician for more information.
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If you have breast cancer and have undergone treatment for it, there is one more thing you can do to increase the odds you will survive the disease: exercise.
The good news is that you do not have to run marathons to reap the benefits: Women who spent three to five hours of walking or two hours of jogging a week cut their risk of death from breast cancer by 50 percent, according to a study in the Journal of the American Medical Association.
"Women with breast cancer have little to lose and much to gain from exercise," says study author Dr. Michelle Holmes, an assistant professor of medicine at Harvard Medical School.
Dr. Holmes was quick to point out, however, that exercise does not replace any form of treatment.
In the study, Dr. Holmes and her colleagues suggest that exercise reduces levels of the hormone estrogen, which acts as a fuel for many breast cancers.
"Estrogen in the body is the primary factor involved in breast cancer and breast cancer risk," says Dr. Debbie Saslow, director of breast and gynecologic cancer for the American Cancer Society. "Anything we do for prevention - losing weight, not drinking alcohol - is directed at lowering estrogen. And, in all populations, physical activity decreases the amount of estrogen circulating in the body."
In a prospective observational study, Dr. Holmes and her colleagues followed breast cancer survivors from two years after their treatment until their death or June 2002, whichever came first.
Almost 3,000 women were included in the analysis. All were enrolled in the ongoing Nurse's Health Study and had been diagnosed with stage I, II, or III breast cancer between 1984 and 1998.
The researchers asked the women about their physical activity seven different times throughout the study period. Their physical activities were assigned a metabolic equivalent score (MET) based on the energy used for that activity. Sitting quietly for an hour is one MET hour, while walking at an average pace of 2 to 2.9 mph for an hour is the equivalent of three MET hours. Jogging for an hour is seven MET hours and running for an hour is 12 MET hours.
Survival benefits were seen starting at 3 to 8.9 MET hours a week. Women who exercised 3 to 8.9 MET hours a week had a 20 percent decrease in the risk of death from breast cancer, compared to women who exercised less than three MET hours a week. Women who exercised 9 to 14.9 MET hours a week cut their risk of dying by 50 percent.
However, greater amounts of exercise than that did not seem to confer greater breast cancer survival benefits.
"Exercise confers a small benefit, but it's there. Every little bit helps, and it's something women can easily do," says Dr. Saslow. Plus, she adds, women should be physically active for the overall health benefits exercise confers, not just to reduce their risk of dying from breast cancer.
"Most women survive breast cancer and die from heart disease later," Dr. Saslow says.
She said the American Cancer Society recommends that anyone who is not currently exercising should try to work up to 30 minutes a day at least five times a week, after checking with their physician to make sure they can safely exercise.
And, she adds, anyone who is already active should aim for 45 minutes to 60 minutes of daily activity that is slightly more than moderately paced most days of the week.
Always consult your physician for more information.
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