Research published in the November 19 issue of The Lancet finds that MRI use for breast cancer screening in women at high risk for the disease – due to family history or a genetic mutation – detects more cancers than screening mammography. The review article also reports that cancers detected by MRI are smaller and less likely to have lymph node involvement than those detected by mammography. These findings provide strong evidence that MRI can benefit this high-risk group. [Read PubMed abstract.]
However, despite MRI being better than mammography at detecting tumors, MRI did not lead to improved outcomes for most women with breast cancer who underwent imaging prior to selecting a treatment.
Memorial Sloan Kettering Breast Surgical Service Chief Monica Morrow, lead author of the article, writes that MRI has become widely used to evaluate newly diagnosed breast cancer patients. The expectation had been that MRI’s higher sensitivity for detecting tumors would benefit patients by more accurately identifying the extent of cancer in the breast.
This would presumably lead to better surgical choices for removing the cancer, reducing the number of operations required, and possibly lowering the risk of the disease recurring. However, a review of patient outcome data from multiple studies found no evidence of such benefits.
“Our study differs from others in that we specifically asked whether MRI findings changed these outcomes for patients,” Dr. Morrow says. “There is no doubt that MRI finds some cancer that is undetected with other imaging methods, but in most patients this has not been shown to help when choosing a type of surgery.”
Evidence suggests MRI is still beneficial for specific groups of breast cancer patients, such as those receiving chemotherapy before surgery and those who have cancer in the lymph nodes without an identifiable breast tumor.
Dr. Morrow adds that the true value of MRI use in breast cancer patients may ultimately lie in its ability to assess how well a specific case of breast cancer is responding to a particular drug treatment, although this needs to be validated by large studies.