Yield of surveillance magnetic resonance imaging after bilateral mastectomy and reconstruction: a retrospective cohort study

Purpose: There are no evidence-based guidelines for surveillance of women after bilateral mastectomy and reconstruction. Several societies recommend against routine breast imaging in this setting. Despite these recommendations, magnetic resonance imaging (MRI) is frequently used to follow these women. We sought to examine the findings on MRI studies done in this setting. Methods: This is a retrospective cohort study including all consecutive MRI exams done after bilateral mastectomy and reconstruction between January 2010 and April 2018. Data collected included demographic information, family history, BRCA status, indication for bilateral mastectomy, type of reconstruction, findings on MRI, and work-up of MRI findings. Cancer detection rate and interval cancer rates were calculated. Results: One hundred fifty-nine women had 415 surveillance MRI exams. Most (372, 90%) studies were done in women with implant-based reconstruction. Four hundred and five (98%; 95% confidence interval (CI) 96–99%) of the studies were negative. One breast recurrence was found on MRI (cancer detection rate 2.4 per 1000 MRI exams, 95% CI 0.4–13); however, this woman was simultaneously diagnosed with metastatic disease. The false-positive rate was 90% (95% CI 54–99%). During follow-up three women were diagnosed with local recurrence (interval cancer rate 5 per 1000, 95% CI 1.3–17) and 4 women were diagnosed with metastatic disease. Conclusion: The yield of surveillance MRI in women with bilateral mastectomy and reconstruction is very low. As most of the cohort had retro-pectoral implant-based reconstruction, it appears safe to recommend against surveillance MRI in this setting regardless of the indication for mastectomy.