The Role of Breast MRI in Detecting Asymptomatic Recurrence After Therapeutic Mastectomy

Abstract

<b>OBJECTIVE.</b> MRI is not routinely used to screen for cancer recurrence after therapeutic mastectomy; however, data on this topic are sparse. We performed this study to determine the utility of breast MRI in detecting asymptomatic locoregional recurrence after therapeutic mastectomy. <b>MATERIALS AND METHODS.</b> A retrospective record review identified all breast MRI studies performed in women who had undergone unilateral therapeutic mastectomy over a 6-year period (January 1, 2010, to January 1, 2016). A total of 402 studies were performed in 191 women between the ages of 26 and 78 years old, none of whom were experiencing symptoms on the mastectomy side. BI-RADS assessments for the mastectomy side were extracted from the radiology reports, and the electronic medical records were reviewed for surgical and oncologic history, clinical and imaging follow-up, and pathologic results. Malignancy was determined by pathologic results. Benignity was confirmed by at least one of the following: pathologic results, at least 12 months of documented disease-free clinical follow-up, or at least 12 months of documented disease-free imaging follow-up. Descriptive statistical and 2 × 2 contingency table analyses were performed. <b>RESULTS.</b> In all, 395 MR images (98.3%) were assessed as showing benign findings on the mastectomy side. Seven (1.7%) were interpreted as showing positive findings on the mastectomy side (BI-RADS category 4, suspicious for malignancy). Biopsy was performed in four of the seven positive interpretations. All four biopsies yielded malignancy for a positive predictive value of biopsy of 100%. The three remaining positive cases did not include biopsy; however, in each case, follow-up imaging showed improvement or resolution of the finding, yielding a positive predictive value of an abnormal examination of 57.1%. Two MRI studies were false-negative, with local recurrence within 12 months after MRI deemed to show benign findings, yielding a negative predictive value of 99.5%. Sensitivity and specificity were 66.7% and 99.2%, respectively. The cancer detection rate in the asymptomatic mastectomy side for all MRI examinations was 10 cancers per 1000 examinations. <b>CONCLUSION.</b> Our findings support inclusion of the mastectomy side in MRI examinations of the contralateral breast to screen for cancer recurrence after therapeutic mastectomy.