Synchronous BI-RADS category 3 lesions detected by preoperative breast MRI in patients with breast cancer: may follow-up be adequate?

Objective The purpose of this study was to analyze the rate of malignancy of synchronous Breast Imaging Reporting and Data System (BI-RADS) category 3 lesions identified by preoperative magnetic resonance imaging (MRI) in patients with breast cancer that were followed up rather than biopsied. Methods From electronic medical records, we identified 99 patients treated in our institution for whom preoperative breast MRI identified synchronous BI-RADS 3 lesions. Lesion characteristics, rate of second-look ultrasonography (US), rate of collegial decision-making, and rate of biopsies performed during the period of monitoring were analyzed. Results Second-look US was performed in 96 of 99 patients and did not reveal any lesion. Collegial decision-making for follow-up validation was asked in 32%. The median time to last MRI was 24.4 months (interquartile range [IQR] [19.3; 36.3]). The median follow-up was 39 months (IQR [28; 52]). Two cancers were diagnosed, one at 5 months and one at 26 months of follow-up. The incidence of malignancy of followed up synchronous BI-RADS category 3 lesions was 1.0% (95% CI [0.1%; 7.1%]) at 6 months and 2.2% (95% CI [0.6%; 8.6%]) at 30 months. Conclusion Monitoring could be proposed for synchronous BI-RADS category 3 lesions detected in preoperative breast cancer patients. A continued follow-up beyond 2 years could be of benefit.