The study reviewed here 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:
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 Breastcancer.org Screening and Testing section.
Adding MRI to conventional breast cancer diagnostic techniques failed to reduce the rate of reoperation for incomplete tumor excision, results of a large randomized clinical trial showed.
The reoperation rate was 19% in patients who had preoperative MRI in addition to clinical, radiologic, and pathologic assessment and in those who had only the usual "diagnostic triad," investigators reported in the Feb. 13 issue of The Lancet.
The findings suggest preoperative MRI has no role in reducing the frequency of reoperation in patients with primary breast cancer, according to Lindsay Turnbull, MD, of the Royal Hull Infirmary in Hull, England, and colleagues.
"Our results show that addition of MRI to conventional triple assessment has no benefit on reduction of reoperation rate," they wrote in conclusion.
"MRI is an expensive procedure," they added. "Because surgical use of MR data to direct wide local excision is similar worldwide, we believe that our findings are generalizable to all healthcare providers, and show that MRI might not be necessary in this population of patients in terms of reduction of reoperation rates."
Studies of dynamic contrast-enhanced MRI in patients scheduled for breast-conserving surgery suggest the imaging results alter clinical management in 14% to 18% of cases, detecting more extensive disease than initially diagnosed. The cost-effectiveness of that application of MRI has not been determined, the authors wrote.
The investigators in the COMICE (COmparative effectiveness of MR Imaging in breast CancEr) trial designed the study to evaluate the efficacy and cost-effectiveness of preoperative contrast-enhanced MRI in women with invasive breast cancer scheduled for wide surgical excision.
The primary endpoint was the proportion of patients undergoing reoperation or further mastectomy within six months of randomization or a pathologically avoidable mastectomy at initial surgery.
The trial involved 1,623 patients enrolled at 45 centers in England. All had biopsy-proven primary breast cancer and were scheduled for wide local excision after clinical, radiologic (by mammography and ultrasound), and pathologic assessment.
The patients were randomized to additional imaging evaluation by MRI or no further preoperative evaluation. MRI was performed according to a standard protocol and with 1.5-Tesla machines.
The authors reported that reoperation was required in 153 of 816 patients (19%) assigned to MRI and 156 of 807 (19%) in the group that did not undergo preoperative MRI. The results translated into an odds ratio of 0.96 (95% CI 0.75 to 1.24, P=0.77).
A change in clinical management based on MRI findings was proposed for 55 patients (7%), 50 of whom subsequently had a change in management because of additional cancer detected on MRI.
In the MRI group, 16 of 58 mastectomies were performed without pathologic confirmation and were considered avoidable and counted in the reoperation rate. That troubling finding diminished the impact of MRI, Elizabeth A. Morris, MD, of Memorial Sloan-Kettering Cancer Center in New York City, wrote in a commentary.
MRI images cancer that is not discovered by other imaging methods, Morris continued. Thus, it seems likely that preoperative MRI may be beneficial in the initial conservative management of the ipsilateral breast in some patient populations.
"COMICE does not fully answer whether preoperative breast MRI adds benefit because recurrence and overall survival were not examined," Morris wrote. "COMICE was designed only to look at reoperation rate. It is a shame that no recurrence data will be obtained."
She also pointed out that "re-excision rates at around 10% are extremely low and should be viewed in context of the wider surgical experience. Attempting to remove the smallest volume of tissue possible, our institutional rate is closer to 25%. With the extremely wide negative margins in COMICE, MRI might have little to add in mapping the area of tumour in this population. With smaller resection volumes with higher re-excision rates, the benefit of using MRI might well be greater."
"A trial as large as COMICE would have the statistical power and potential to examine the possibly more important outcome of recurrence," she added. "Because the question of recurrence and overall survival is still unanswered, the complete role of preoperative breast MRI is not yet defined."
The study was funded by the National Institute for Health Research.
The authors had no relevant disclosures.
Primary source: The Lancet Source reference: Turnbull L, et al "Comparative effectiveness of MRI in breast cancer (COMICE) trial: a randomized controlled trial" Lancet 2010; 375: 563-71.Additional source: The LancetSource reference: Morris EA "Should we dispense with preoperative breast MRI?" Lancet 2010; 375: 528-30.
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