The impact of MRI on the treatment of DCIS.

Magnetic resonance imaging (MRI) has been shown to detect occult invasive breast cancers with a sensitivity of 97 per cent to 100 per cent. Mammography and ultrasonography does not accurately assess the extent of ductal carcinoma in situ (DCIS), which results in a high reoperation rate. Breast MRI can improve the surgical planning in women with DCIS, improving the adequacy of initial treatment while reducing reoperation. We examined 54 patients with predominantly DCIS (> 50%) who underwent breast MRI from January 2003 to November 2004. MRI altered the surgical management in 14 (26%) patients: unilateral changed to bilateral mastectomy (5); lumpectomy or reexcision to mastectomy (3); unilateral lumpectomy or mastectomy had additional biopsies for lesions detected by MRI in the ipsilateral or contralateral breast (6). There were 8 true-positives and 7 false-positives: sensitivity 86 per cent, positive predictive value 84 per cent. MRI changed the surgical management to more appropriate therapy in 15 per cent of patients avoiding additional surgery, while 11 per cent underwent negative surgical interventions. Breast MRI is a sensitive diagnostic imaging tool in patients with DCIS. However, any suspicious finding should be biopsied before a definitive operation is planned.