Commentary (Bartella): The Application of Breast MRI in Staging and Screening for Breast Cancer

One of the major roles of breast MRI in clinical practice has been in the evaluation of disease extent. The roles of mammography and sonography can be limited, especially in the presence of invasive lobular carcinoma and in the patient with positive margins postoperatively. Breast MRI has improved our detection of multicentric, multifocal, and concurrent contralateral disease. Dr. Gundry correctly stresses that the role of mammography is not replaced by breast MRI, and that suspicious calcifications should be biopsied in the absence of suspicious enhancing lesions on MRI. Limitations of MRI with regard to ductal carcinoma in situ (DCIS) diagnosis and in the presence of stippled enhancement in the young premenopausal patient are becoming increasingly evident. As additional disease is now detected by breast MRI, we have seen changes in recommended and chosen surgical management. In a recent review of MRI-detected invasive breast cancers performed at Memorial Sloan-Kettering Cancer Center (MSKCC),[1] 68% of the patients were treated with mastectomy. This is a much higher percentage than the average 20% to 25% traditionally performed at MSKCC. This 43% to 48% increase in mastectomy rate obviously raises some serious issues including considerations of mortality and morbidity. Although we cannot be certain that breast MRI reduces mortality rates, we can be certain that it detects more cancers. Knowing that the main principle underlying local management of breast cancer is to excise all cancer prior to adjuvant chemotherapy or radiation, the role of MRI is clearly important. The role of MRI in detecting mammographically occult primary cancers in the setting of known metastasis has also been well discussed. When the primary tumor can be identified, breast conservation can be performed without influencing survival. Also, in the setting of more advanced metastatic disease, appropriate chemotherapy can be much more effective when the primary site of malignancy is known. Thus far, breast MRI has been shown to be the most accurate method in assessing response to neoadjuvant chemotherapy. As the author nicely explains, response can be indicated not only by a change in the size of the tumor but also by a change in its kinetics. Such assessment has been a valuable tool in the management of locally advanced disease.