After early-stage breast cancer is diagnosed, some doctors order a breast MRI (magnetic resonance imaging) to help decide between mastectomy or lumpectomy. The MRI is done to learn more information about the breast cancer, but there isn't good evidence that routinely using MRI in this way improves the doctor's recommendations, the care a woman receives, or the outcome of the treatment.
Results from a study echo what other studies have shown: an MRI after early-stage breast cancer diagnosis and before surgery didn't really help doctors make better decisions about whether mastectomy or lumpectomy was the best option for a woman. The study found that the MRI caused false positives and may have led to more women having a mastectomy even though a lumpectomy followed by radiation therapy may have been a good option. A false positive is an abnormality that looks like a cancer, but turns out to be normal.
The researchers looked at a number of studies analyzing the use of MRI after a diagnosis of early-stage breast cancer:
- Depending on the study, about 3% to 22% of the women had their surgery change from lumpectomy to mastectomy based on MRI results. The researchers noted that many of the additional abnormalities identified by the MRI were false positives.
- There was no difference in the number of positive margins (cancer cells found in the very edge of the tissue that is removed, which usually means more tissue is removed) between women who had MRI before surgery and women who didn't have MRI before surgery.
- One study suggested that women who had MRI before surgery had a lower risk of the cancer coming back in the same breast (local recurrence) compared to women who didn't have MRI before surgery, but another study found no difference in local recurrence or overall survival between the two groups.
These results don't mean that having an MRI before surgery is a bad idea. The results suggest that ROUTINELY doing an MRI before surgery may not make sense; routinely doing MRI before surgery may lead to more mastectomy recommendations than lumpectomy recommendations with no improvement in outcome.
If you've been diagnosed with early-stage breast cancer and your doctor recommends an MRI to help make choices about surgery, ask your doctor why MRI is being recommended and how the results will help your care.
You can learn much more about tests to evaluate breast cancer, including MRI, in the Breastcancer.org Screening and Testing section.