MRI Before Surgery Doesn’t Reduce Need for More Surgery Later

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A study found that having an MRI before breast cancer surgery doesn’t reduce the likelihood that a woman would need more breast cancer surgery later.

The study was published in the September 2012 issue of Archives of Surgery. Read the abstract of “Selective Preoperative Magnetic Resonance Imaging in Women With Breast Cancer: No Reduction in the Reoperation Rate.”

When planning surgery to remove early-stage breast cancer, 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 test 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 doctors’ recommendations, a woman’s care, or surgery outcomes. Even with a large amount of information available before the operation, some women will have to have more surgery after the biopsy results from the tissue removed during surgery are available.

This study analyzed the surgery results of 313 women diagnosed with early-stage breast cancer who all had breast cancer surgery done by the same surgeon in North Carolina. The women weren’t randomly assigned to get an MRI before surgery. Instead, 120 women who were thought to be candidates for lumpectomy, but had dense breasts got an MRI before surgery.

Dense breasts have less fatty tissue and more non-fatty tissue compared to breasts that aren’t dense. Doctors can tell if breasts are dense by the way they look on a mammogram.

Research has shown that dense breasts:

  • can be 6 times more likely to develop cancer
  • can be harder for mammograms to detect cancer in; breast cancers (which aren’t fatty) are easier to see on a mammogram when they’re surrounded by fatty tissue

The researchers then compared how many women in each group (those who had MRI before surgery and those who didn’t) needed more breast cancer surgery some time later:

  • 19.1% of women who had an MRI before their initial breast cancer surgery had more surgery later
  • 17.6% of women who didn’t have an MRI before initial breast cancer surgery had more surgery later

Of the women who had MRI before surgery, 47 had mastectomy instead of lumpectomy. Based on the pathological information available after surgery, lumpectomy followed by radiation therapy would have been a good, less aggressive option for 12 (about 25%) of these women. It may be that doing an MRI before initial breast cancer surgery resulted in unnecessarily aggressive surgery for some women.

It’s important to know that several factors make the results of this study somewhat questionable:

  • The women weren’t randomly assigned to get an MRI before breast cancer surgery. This means that there could have been some bias in selecting the women who got an MRI.
  • The women were all operated on by the same surgeon. This is limiting because we can’t say for sure what happens in one practice is what’s happening everywhere.
  • The study was retrospective, which means the results are based on treatment plans developed before the study was planned.

Doctors are usually more confident in the results of a study where the treatment plans are part of the study design and randomly assigned to participants.

Also, this study 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, 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 initial breast cancer surgery.

It's important to know that this study doesn't mean having an MRI before surgery is a bad idea for everyone. 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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