The mammography has been the only regularly advised imaging test for the detection of breast cancer for many years. Mammograms, which use X-rays to check within the breast, are indicated for all women over 40, regardless of risk level, at least every other year. High-risk females should start early and undergo more frequent testing. This level of care has become the norm. But in March 2007, material urging the inclusion of MRI, a magnetic imaging method, in the usual testing protocols for specific women, was made public by two separate sources.
The most significant news is a set of recommendations made by the American Cancer Society, which recommends adding MRIs to the routine, yearly testing schedule for women who are in the high-risk group for breast cancer. MRIs are an additional tool that can find certain malignancies that mammography miss; they do not take the place of annual mammograms. However, there are drawbacks to breast MRIs that make them less desirable for any woman who is not in the high-risk category.
A breast MRI produces numerous images of the breast from every aspect using magnets and radio waves. In the MRI scanner, where the patient lies for 30 to 60 minutes, a very powerful magnet creates a magnetic field and alternately changes its orientation as the machine pulses radio waves into the breast tissue. A magnetic coil encircling each breast monitors how strongly the radio waves are reflected back by the various layers of breast tissue. The device provides views of the breast on every axis—side to side, front to back, and top to bottom—by varying the magnetic field's orientation throughout the inspection.
The use of MRI has many advantages. First, unlike a mammography, there is no radiation involved. Additionally, because the breast doesn't need to be flattened, it is less unpleasant than a mammography. The major benefit is that an MRI can detect many more problems than a mammography. It is unaffected by breast tissue that is particularly dense, which the majority of young women have, or by breast implants, both of which might mask a tumor on a mammography. Additionally, compared to a mammography, it photographs the breast on multiple planes, providing a much more thorough view that can detect even minute variations in breast density that may be signs of cancer.
However, the breast MRI's biggest feature is also its worst drawback. It virtually picks up everything. An MRI will show anything that even the tiniest bit seems off. However, there are a ton of strange-looking things that appear on breast scans and are unrelated to cancer. According to some estimates, one in ten MRI results are false positives, causing women to undergo numerous invasive biopsies and needless cancer screenings. Because of this, MRIs are not advised for women who fall into the average-risk category. Going through a diagnostic process that results in a false positive 10% of the time doesn't make sense unless there's a really strong chance you're going to acquire breast cancer.
Although MRI does not use radiation, it does require the infusion of a dye to provide more contrast on the images, and it has difficulty detecting some forms of calcifications that may be cancerous. These calcifications can be seen on mammograms. Additionally, MRI scans can be uncomfortable for claustrophobic patients for up to an hour, and they are around ten times more expensive than mammograms. Some insurance policies do cover it, while others do not. If her insurance won't cover it, a woman in the high-risk group would need to spend at least $1,000 a year on a breast MRI. Which takes us to a different issue: identifying the high-risk category.
Breast Cancer Susceptibility
How breast cancer risk should be calculated is a question that no one can definitively answer. Although risk factors are largely qualitative, a 20% chance of developing breast cancer is commonly considered to be "high risk." According to the majority of recommendations, high-risk women are those who are over 30 and have:
- more than one close relative has battled breast cancer (mother, sister, daughter).
- a gene change related to breast cancer (a mutated BRCA1, BRCA2, TP53 or PTEN gene)
- a close family with a breast cancer-related genetic mutation
- after the age of ten and before the age of thirty, radiation therapy to the chest
Even with these recommendations, the only way to determine if you truly fall into the high-risk category is to speak with your doctor. Some females who fit one or more of these descriptions are really in the average-risk category and do not require an annual MRI. A recent study that was published in the New England Journal of Medicine is the second source that advocates for the routine use of MRI in breast-cancer testing. However, this study actually only pertains to women who have already been given a breast cancer diagnosis. According to this recent study, women who have been told they have breast cancer in one breast should undergo an MRI of the second breast right away, even if the mammogram is negative, before starting cancer therapy.
The study included 969 women who had mammography results showing no malignancy in the other breast but had been diagnosed with a malignant tumor in one breast. After that, an MRI of the breast that wasn't malignant was performed on each woman. The MRI revealed that there was cancer in the other breast in 30 of the instances. Without the MRI, those 30 women, or 3% of the research participants, might have started treatment for breast cancer in one breast only to discover later that it had spread to the other breast.
The woman might have had to undergo a full second round of treatment involving surgery, chemotherapy, and/or radiation because the second cancer would have been found at a later stage, making it more serious. In terms of cancer, a 3% probability of a false negative is unacceptable if it can be prevented with a quick, non-invasive surgery. It's possible that insurance companies that don't now cover the treatment will start doing so very soon given the recent publication of two reliable recommendations for MRI as a routine breast-cancer diagnosis approach.