Breast Cancer: MRI and Early Detection

Many experts believe that mammograms save lives. But some healthcare professionals argue that mammograms are not enough for certain women at high risk for breast cancer. Studies suggest that MRIs (magnetic resonance imaging) may improve the early detection of cancer in women at high risk.

Current screening guidelines for women at high risk

According to the American Cancer Society, you are considered at high risk for breast cancer if any of the following statements are true:

• You have a parent, brother, sister, or child (a first-degree relative) with a known BRCA1 or BRCA2 gene mutation. But you have not had genetic testing done yourself.

• You tested positive for genetic changes that increase the risk for breast cancer—BRCA1 or BRCA2 mutations.

• Your healthcare provider estimates that you have a lifetime risk of breast cancer of 20% to 25% or greater, according to risk assessment tools based mainly on your family history.

• You had radiation therapy to the chest when you were between ages 10 and 30.

• You have Li-Fraumeni syndrome, Cowden syndrome, or Bannayan-Riley-Ruvalcaba syndrome. Or a first-degree relative has one of these syndromes.

If you're a woman at high risk for breast cancer, you should ask your doctor if you should have more frequent screenings, with a variety of tests, starting at a younger age. Breast cancer screening means checking for it in women who don't have any symptoms. For women at high risk, some experts recommend clinical breast exams every 1 to 3 years, and yearly mammography starting at about age 30. Women at high risk should also have breast self-awareness. This means having a sense of what's normal for your breasts so that you can notice changes and see a provider right away. The American Cancer Society recommends that women known to be at high risk get an MRI and a mammogram every year, starting at age 30.

How MRIs Work

Instead of the X-rays used in mammography, an MRI uses magnets and radio waves connected to a computer to make many detailed pictures of the inside of the breast. You may be given a contrast dye to better outline the breast tissue and possible tumors. The dye is put into a vein in your hand or arm.

MRIs can find tumors that are too small to feel and may not show up on a mammogram. But an MRI may miss some cancers that would be found on a mammogram. So it's important that high-risk women get both tests.

One reason MRIs may find these tumors is because high-risk women tend to be younger and have denser breasts. This means that the breast has less fat and more fiber-like connective tissue, which can block X-rays during a mammogram. An MRI is not affected by dense, fibrous breast tissue.

Drawbacks of MRIs

It's important to weigh the pros and cons of MRIs for certain groups of high-risk women. Here are some of their drawbacks:

• MRIs may have a high rate of false positives. A false positive means it looks like cancer but is not. MRIs are more sensitive, which means they are more likely to find tissue changes that turn out to not be cancer. This leads to further testing to find out if the changed area is actually cancer. These tests may include another MRI, other tests, or biopsies.

• MRIs are costly. They require special breast MRI equipment and a radiologist trained in breast imaging to interpret the images. Possible follow-up tests or biopsies add to the costs.

• Women may have an allergic reaction to the contrast dye. The dye injected before an MRI can possibly, though rarely, cause an allergic reaction. In some people the thought of having an injection can increase anxiety.

• The MRI machine makes some people uncomfortable. The narrow tube-like MRI machine may cause anxiety and discomfort especially in people who are claustrophobic.