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.
The results from the study reviewed here 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 reviewed here 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:
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.
Preoperative MRI scans for newly diagnosed, early stage breast cancer may reduce a woman's chances of conservative surgery without any improvement in either outcomes or the need for follow-up surgery, a review found.
The highly sensitive imaging technique detects 16% more cancer foci than traditional staging methods, typically leading to more radical surgery, according to Nehmat Houssami, MBBS, PhD, of the University of Sydney, Australia, and Daniel F. Hayes, MD, of the University of Michigan Comprehensive Cancer Center in Ann Arbor.
However, "emerging data indicate that MRI does not reduce re-excision rates and that it causes false positives in terms of detection and unnecessary surgery; overall, there is little high-quality evidence at present to support the routine use of preoperative MRI," they wrote online in CA: A Cancer Journal for Clinicians.
The assumption was that better detection and delineation of the boundaries of breast tumors would improve surgical planning or precision and reduce in-breast recurrences by eliminating disease that would have otherwise been missed, the researchers said.
Conventional staging with clinical assessment and mammography misses additional foci of cancer in 20% to 60% of affected breasts, compared with pathology.
However, clinical trials have shown that breast conserving surgery nonetheless produces the same survival rates as mastectomy since subsequent adjuvant radiation eradicates unrecognized cancerous tissue left behind.
The long-term risk of local recurrence is higher than with mastectomy but still low, typically 0.5% to 1% per year.
"Thus, the goal is to ... achieve good local control, and to provide women who wish to conserve their breast a good cosmetic outcome," the researchers said.
Anything that would impair a woman's chances for breast-conserving surgery, "must be given very carefully and should be based on evidence that this will improve clinical outcomes," they added.
Pooled results from trials reporting a change in surgical management for breast conservation surgery candidates attributed to MRI, based on detection of additional malignant lesions, indicated 11.3% had more extensive surgery than initially planned.
Rates for change to mastectomy ranged from 2.4% to 22.2%, and change to wider excision was seen in an additional 3.2% to 13.9%.
In these trials, though, histology revealed that many changes were unnecessary because the extra lesions detected by MRI were false positives.
One meta-analysis suggested one false positive for every 1.9 true positives detected by MRI.
In the pooled analysis of surgical management trials, 5.5% of women had wider excision or mastectomy prompted by false positives.
Reoperation, re-excision, and positive margins were no more common for women who didn't have preoperative MRI than for those who did in the few trials to evaluate this outcome (P=0.17 to P=0.77).
With regard to long-term outcomes, one retrospective study suggested a lower local recurrence rate with preoperative MRI (1.2% versus 6.8% at 40 months, P<0.01), but another indicated no difference at eight years in local recurrence (3% versus 4%; P=0.51), local-only first site of recurrence (3% versus 4%; P=0.32), or overall survival (86% versus 87%; P=0.51).
Houssami and Hayes suggested similar arguments apply to use of MRI for contralateral breast assessment.
"Routine use of preoperative MRI in women with established, early stage breast cancer should be discouraged until (and if) high levels of evidence demonstrate that preoperative MRI either improves surgical care, reduces the number of required surgeries, or (more importantly) that it reduces at least local recurrence, if not distant metastases and death due to breast cancer," they concluded.
Houssami reported funding by a grant from the National Health and Medical Research Council to the Screening and Test Evaluation Program.
Hayes reported support by the Fashion Footwear Charitable Foundation of New York/QVC Presents Shoes on Sale.
Primary source: CA: A Cancer Journal for Clinicians Source reference: Houssami N, Hayes DF "Review of preoperative magnetic resonance imaging (MRI) in breast cancer: Should MRI be performed on all women with newly diagnosed, early stage breast cancer?" CA Cancer J Clin 2009; 59: DOI: 10.3322/caac.20028.
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