American women know the value of breast cancer early detection from the 25-year-old breast cancer awareness movement. The three major breast cancer screening messages have been told loudly and clearly:
- Mammography every year starting at age 40 (but earlier for women with a family history of breast cancer at a young age).
- Regular breast examination by your doctor.
- Breast self-examination.
But no test or combination of tests is perfect. Even with these three tools, some breast cancers escape detection. Research has shown that between 10% and 15% of breast cancers can be missed even when all three tests are done. Until the breast cancer cure arrives, we need more tools to help detect all breast cancers as early as possible when they are most treatable. Also, women diagnosed with breast cancer in one breast have a higher risk of developing another cancer in the same or the opposite breast. A better approach to detecting a new or existing cancer is hugely important for these women.
A study looked at how well breast MRI (magnetic resonance imaging) could detect cancers in the other breast of women just diagnosed with breast cancer. MRI uses magnetic fields to highlight different kinds of tissues, both normal and abnormal. In almost 1,000 women diagnosed with cancer in one breast, an MRI scan was able to detect breast cancer in the other breast of 3% of the women (30 out of 969) that was missed by mammography and clinical examination.
Based on the results of this and another study, the American Cancer Society (ACS) now recommends that women diagnosed with cancer in one breast have an MRI scan of the other breast to make sure there is no cancer there. The ACS also recommends an annual MRI scan for women who are at high risk for breast cancer because they have:
- a known breast cancer gene (BRCA1 or BRCA2)
- a first-degree relative (parent, sibling, child) with a BRCA1 or BRCA2 mutation, even if they haven't been tested
- a lifetime risk of breast cancer score of 20-25% or higher, based on specific risk assessment tools that look at family history and other factors (this can be determined with the help of your doctor)
- had chest radiation between the ages of 10 and 30
- certain medical conditions or have a first-degree relative that has them, including Li-Fraumeni syndrome, Cowden syndrome or Bannayan-Riley-Ruvalcaba syndrome
When breast cancer is diagnosed, it's important to carefully evaluate both breasts. You and your doctor may understandably focus only on the breast with the cancer. But knowing what's happening in both breasts (and in your whole body) will help you and your doctors determine the best treatment strategy to get rid of the cancer. Early detection also may help you avoid some treatments that you might otherwise need with a later diagnosis.
It's important to know that MRI is a very sensitive test that can lead to many false alarms. Of the 121 women in this study whose MRI scan showed an abnormality, 30 had cancer; about 25%. That means that about 75% of the women had an MRI abnormality that WASN'T cancer.
The bottom line is that if you've been diagnosed with breast cancer or are at high risk for having breast cancer, an MRI scan is an important additional tool to carefully evaluate both breasts. Information from an MRI scan may help detect breast cancer earlier in high-risk women and may be important in determining the best treatment plan for women already diagnosed with breast cancer. Still, MRI doesn't replace a breast exam by your doctor and mammography. These techniques are important front-line tools for all women.