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.

Key Points: • Follow-up can be proposed for MRI BI-RADS category 3 lesions not detected at second-look ultrasound, possibly after a collegial decision. • Follow-up should be continued annually since cancer may occur beyond 2 years.