Risk-benefit analysis of preoperative breast MRI in patients with primary breast cancer

To analyse and compare the risks and benefits of preoperative breast MRI (BMRI) in patients with primary breast cancer (PBC), and to determine the influence of mammographic breast density (BD) and histological tumour type (TT).

One hundred and nineteen patients who underwent preoperative bilateral breast MRI for staging of PBC during a 1-year period from July 2005 to August 2006 were prospectively evaluated. Changes in clinical management due to BMRI findings were recorded. MRI-detected lesions were correlated with histology. Additional MRI-detected malignant lesions and spared additional biopsies because of negative MRI in case of unclear ultrasound findings were determined as beneficial for the patient. Biopsies of benign MRI detected lesions were defined as disadvantageous. The influence of BD (ACR 1-4) and TT on the change in clinical management and patient benefit was evaluated.

The findings of the BMRI examinations changed the clinical management in 48 patients (40.3%). Seventeen women underwent mastectomy instead of breast conservation, eight patients underwent extended excision, 21 additional lesions were clarified by MRI intervention, and two ultrasound-detected lesions were not biopsied because of negative MRI. Histologically malignant additional or extended biopsies (n=34) and two cases of spared biopsies resulted in 36 (30.3%) women who benefited from preoperative BMRI. Twelve patients (10.1%) had additional biopsies of MRI-detected benign lesions, and therefore, had an unfavourable outcome due to BMRI. The change in clinical management and patient benefit were independent of BD and TT (p>0.05).

Preoperative BMRI was beneficial for 30.3% of 119 patients with PBC. The percentage of additional biopsies of benign lesions (10.1%) seems acceptable.