Preoperative MRI Improves Surgical Planning and Outcomes for Ductal Carcinoma in Situ.

D carcinoma in situ (DCIS) is a heterogeneous group of lesions that differ with regard to histopathologic features, biologic markers, and genetic and molecular abnormalities. It is defined as “a neoplastic proliferation of epithelial cells confined to the ductallobular system and characterized by subtle to marked cytological atypia and an inherent but not necessarily obligatory tendency for progression to invasive breast cancer” (1). Whereas some DCIS may not or may only progress slowly to non–high-grade invasive breast cancer, some DCIS will progress rapidly to high-grade invasive breast cancer. Surgery is the most common treatment for DCIS, but it is also controversial and may be overtreatment. There is no current diagnostic means that can determine which DCIS will develop into invasive breast cancer. DCIS was traditionally a “mammographic disease. ” DCIS initially accounted for only 1%–2% of breast cancers, but there has been a significant increase in incidence particularly in women of screening age with the implementation of population-based screening programs (2). Approximately 20% of all screen-detected breast cancers are DCIS that typically manifest with suspicious microcalcifications or less often as masses or architectural distortions at screening mammography (3). Nevertheless, although mammography for DCIS is a success story, DCIS remains a diagnostic challenge. The adequate assessment of calcifications is only possible with invasive tissue sampling (ie, vacuum-assisted core biopsy). However, vacuum-assisted core biopsy is often unnecessary due to false-positive diagnoses, showing a positive predictive value for suspicious calcifications ranging from 25%–40%. In addition, high-grade DCIS clustered calcifications in particular are often a poor indicator of actual lesion extent (known as the “tip of iceberg” phenomenon), leading to inadequate presurgical localization and subsequent re-excision for negative margins. Pathologists note that the vast majority of breast cancers evolve through the ductal stage. Yet even in women who attend annual screening with mammography, 80% of breast cancers are diagnosed at the invasive stage, indicating that screening mammography fails to help diagnose the majority of DCIS stages. Moreover, more than half of invasive breast cancers are not associated with calcifications. In summary, there is an overdiagnosis of biologically inert DCIS and an underdiagnosis of prognostically relevant DCIS. The European Society of Breast Cancer Specialists recommendations for breast MRI that date from 2010 (4) state that the acceptable indications for preoperative MRI are limited to the following indications: (a) patients newly diagnosed with an invasive lobular cancer (level of evidence [LoE], 2a; degree of recommendation [DoR], B) by using the methodology defined by the Centre for Evidence-based Medicine, Oxford, England); (b) patients at high risk for breast cancer (LoE, 2b; DoR, B); (c) patients younger than 60 years with discrepancy in size greater than 1 cm between mammography and breast US with an expected impact on treatment decision (LoE, 2b; DoR, B); and (d) patients eligible for partial breast irradiation on the basis of clinical breast examination and conventional imaging with mammography and sonography (LoE, 3b; DoR, B). Most of the evidence to support these indications stems from the era when the possibilities to perform MRI-guided biopsies to verify the MRI findings were not widely available (comparative effectiveness of MRI in breast cancer [COMICE] trial, ISRCTN number 57474502) or important methodologic biases were overlooked (MR mammography of nonpalpable breast tumors [MONET] trial, NCT00302120). To date, there is a compelling body of evidence that breast MRI is the method with the highest diagnostic accuracy for the detection and staging of breast cancer. Breast MRI is the most sensitive modality currently available for identifying DCIS. Breast MRI is more Preoperative MRI Improves Surgical Planning and Outcomes for Ductal Carcinoma in Situ