Women often ask their doctors whether they should have another test, in addition to a mammogram, when they are being screened for breast cancer. It may seem logical to think that if every woman had routine screening by breast MRI, it would result in earlier diagnosis and treatment of cancer. However, because breast MRI is a very sensitive test, it will find even tiny lumps in the breast.

Well, finding everything in the breast is a good thing, right? Not necessarily!

In the average-risk woman, most of the lumps and bumps found on breast MRI turn out to be nothing of concern. Unfortunately, making that determination can require a patient to undergo several biopsies and, in the meantime, experience a great deal of mental anguish.

Therefore, because of the sensitivity of this test, breast MRI is reserved only for women who are considered at high risk for breast cancer or for those women who have already been diagnosed with breast cancer and are at high risk for another cancer elsewhere in the breasts. The American College of Radiology guidelines recommend breast MRI for the following groups of women:

• Women with 20% or greater lifetime risk of cancer (This risk is calculated using a mathematical model that considers answers to questions such as the following: How many relatives with breast cancer do you have? How old you were when you started your period? How old you were when you had your first baby?)
• Women who have just been diagnosed with breast cancer and now need a more detailed look at the rest of the breasts
• Women with breast implants in whom mammogram is difficult (An experienced mammographer, however, can obtain a good mammogram in women with implants.)
• Women in unique situations, such as those with cancer remaining in the breast despite having had surgery or those with possible cancer in a reconstructed breast

Women who do not fall into the above categories probably do not need breast MRI and in fact may be harmed by breast MRI if it leads to a lot of unnecessary tests and biopsies.

Being female and aging are the 2 most important risk factors for the development of breast cancer. However, women with only these 2 risk factors are considered average risk, and do not need screening breast MRI.

• You have a first-degree family relative (mother, sister, or daughter) or many other relatives with breast cancer on either side of the family.
• You had your first baby after age 35 or have never had children.
• You have had previous breast biopsies, especially if those results showed DCIS, LCIS, ADH, or ALH.
• You have a family member with BRCA1 or BRCA2, sometimes referred to as “the breast cancer genes.”

These risk factors may indicate that you have a higher risk of breast cancer than the average woman. Your doctor can assess your risk for developing breast cancer and determine if a breast MRI is appropriate in your case.

The American Society of Breast Surgeons’ Consensus Statement

Consensus Guideline on Diagnostic and Screening Magnetic Resonance Imaging of the Breast