- “We must take the lead in the battle against breast cancer”
Robert L. Barbieri, MD (Editorial; July 2009)
The use of magnetic resonance imaging (MRI) for breast cancer screening and to guide treatment decisions is increasing—with little evidence that it is beneficial in those settings, according to the findings of a recent study.1 Although MRI was shown to be a valuable tool for screening women who are at genetically high risk of breast cancer, the investigation produced limited support for its 1) use in screening women in the general population and 2) routine use before breast-conserving surgery to guide patient selection, reduce surgical procedures, or lower the risk of local recurrence.
Morrow and colleagues from Memorial Sloan-Kettering Cancer Center reviewed research from the past decade to determine whether the increased sensitivity of MRI in the detection of cancer actually improves outcomes. Over recent years, MRI has been widely incorporated into clinical practice because of its heightened sensitivity.
There is sufficient evidence that MRI is a beneficial tool for screening women at high risk of breast cancer because of their family history or a known gene mutation. The modality can accurately identify tumors missed by mammography and ultrasonographic imaging. However, little is known about whether this improved detection has an impact on survival.
Morrow and colleagues conclude that the existing data “do not support the idea that MRI improves patient selection for breast-conserving surgery or that it increases the likelihood of obtaining negative margins at the initial surgical excision.”
Furthermore, the impact of MRI on longer-term outcomes, such as the incidence of contralateral cancer or the recurrence of ipsilateral cancer, cannot be established because of the limited number of trials, many of which are of low quality.
Research does suggest, however, that MRI is more reliable than traditional examinations (i.e., physical examination, mammography, and ultrasonography) at assessing the extent of residual disease after preoperative chemotherapy, as well as the response to preoperative chemotherapy. But whether this improves the surgeon’s ability to select patients suitable for breast-conserving therapy is unclear.
“Ultimately, the true value of MRI might lie in its ability to predict biological behavior, rather than to quantitate low-volume disease,” the investigators conclude. “Very early changes in intracellular metabolism that are detectable by magnetic resonance spectroscopy seem to be predictive of the response to treatment, and, if validated in larger studies, could avoid the toxicity and expense of continuing a chemotherapy regimen that will not be beneficial.”
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