Nodal positivity in breast cancer correlated with the number of lesions detected by magnetic resonance imaging versus mammogram

Abstract Background Magnetic resonance imaging (MRI) in breast cancer can detect more than 15% additional lesions than mammography. We investigated lymph node metastases rates in patients with multifocal or multicentric disease detected by MRI compared with patients with a single lesion detected by mammography and magnetic resonance imaging. Methods A retrospective analysis of breast cancer patients undergoing MRI and mammography was performed. The objective was to compare lymph node metastases rates in patients with additional lesions detected by MRI versus a single lesion detected by mammography or MRI. Results Of 413 patients, 318 were included for the study. The overall nodal metastases rate was 24.8%. MRI detected multiple lesions in 83 (26.1%) patients; 67 (21.1%) patient MRI findings were not detected by mammography. The lymph node metastases rate was 37.3% when ≥2 lesions were detected compared with 20.2% when a single malignant lesion was detected ( P = .01). The evaluation of the 67 patients with additional lesions detected by MRI revealed 32 patients with invasive lesions, 29 with benign lesions, and 6 with in situ disease. Comparing patients with single malignant lesions with patients with additional malignant lesions detected by MRI, the lymph node metastases rate increased from 20.2% to 50% ( P = .002). Conclusions Our study shows a significant increase in the lymph node metastases rate in patients with additional malignant lesions detected by MRI. This finding suggests that MRI-detected malignant lesions are biologically significant and may predict more aggressive disease.