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MRI Before Breast Cancer Surgery Doesn’t Lower Reoperation Rate

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A study suggests that doing MRI before a first breast cancer surgery doesn't reduce the likelihood that a woman would need more breast cancer surgery within 6 months.

When planning early-stage breast cancer surgery, you and your doctors must decide on the type of surgery (lumpectomy or mastectomy) and if any lymph nodes will be removed. Doctors commonly use:

  • information from a physical exam
  • standard breast imaging study results (mammography and ultrasound)
  • biopsy results

to help make these decisions. Some doctors also use breast MRI results.

But there really isn't good evidence that routinely using MRI results to decide on early-stage breast cancer surgery improves doctor recommendations, a woman's care, or surgery outcomes. Even with a large amount of information available before initial breast cancer surgery, some women will have to have more surgery after biopsy results from the tissue removed during surgery are available.

This study, called COMICE (COmparative effectiveness of MR Imaging in breast CancEr), 1,623 British women diagnosed with early-stage breast cancer had a physical exam, mammogram, ultrasound, and biopsy to help make decisions about surgery. About half the women also had a breast MRI before surgery.

The researchers compared women who did and didn't have an MRI to see if there were differences in the likelihood that a woman would need more breast cancer surgery within 6 months of the first surgery. The researchers also wanted to know if women who had MRI and then had mastectomy as the first surgery could have safely chosen lumpectomy followed by radiation therapy.

Overall, 19% of the women needed more breast cancer surgery within 6 months of the first surgery, no matter if they had MRI or not. So MRI didn't seem to reduce the risk of needing more surgery.

Of the women who had MRI, 58 had mastectomy instead of lumpectomy. Based on the information available before and after surgery, lumpectomy followed by radiation therapy would have been a good, less aggressive option for 13 (28%) of these women. It may be that doing an MRI before the first breast cancer surgery resulted in unnecessarily aggressive surgery for some women.

Breast MRI is considered more sensitive than mammography in identifying breast cancer, but MRI also can miss some cancers that mammography and ultrasound can detect. Looking at a cancer with as many different imaging tests as possible before surgery might seem to make sense. But false positives are one of the risks of using many different tests. A false positive is an area that looks suspicious but turns out to be normal. More sensitive tests, such as MRI, tend to produce more false positives compared to mammograms and ultrasounds. This may be why some women who had MRI before surgery had unnecessarily aggressive surgery.

The risk of more false positives might be acceptable if MRIs improved the overall outcome of breast cancer surgery. But this study only followed the women for 6 months and didn't look at overall survival or the risk of the cancer coming back (recurrence). While the study suggests that MRI doesn't reduce the need for more surgery within 6 months, it's possible that MRIs before surgery might lead to a lower risk of recurrence or better survival. More research is needed to study the long-term benefits of MRIs before a first breast cancer surgery.

It's important to know that this study doesn't mean having an MRI before surgery is a bad idea. The results suggest that ROUTINELY doing an MRI before surgery may not make sense; regularly doing MRI before surgery may lead to more unnecessarily aggressive surgery without reducing the need for more surgery in the future.

If you've been diagnosed with early-stage breast cancer and your doctor recommends an MRI to help make surgery decisions, you might want to ask your doctor about the benefits of MRI for your unique situation and how the results will improve your care.

You can learn much more about tests for breast cancer, including MRI, in the Screening and Testing section.

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