Abstract
BACKGROUND: Magnetic resonance imaging can be used to diagnose breast cancer (BC). Diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC) can be used to reflect tumor microstructure. OBJECTIVES: This analysis aimed to compare ADC values between molecular subtypes of BC based on a large sample of patients. METHOD: The MEDLINE library and Scopus database were screened for the associations between ADC and molecular subtypes of BC up to April 2020. The primary end point of the systematic review was the ADC value in different BC subtypes. Overall, 28 studies were included. RESULTS: The included studies comprised a total of 2,990 tumors. Luminal A type was diagnosed in 865 cases (28.9%), luminal B in 899 (30.1%), human epidermal growth factor receptor (Her2)-enriched in 597 (20.0%), and triple-negative in 629 (21.0%). The mean ADC values of the subtypes were as follows: luminal A: 0.99 × 10(-3) mm(2)/s (95% CI 0.94-1.04), luminal B: 0.97 × 10(-3) mm(2)/s (95% CI 0.89-1.05), Her2-enriched: 1.02 × 10(-3) mm(2)/s (95% CI 0.95-1.08), and triple-negative: 0.99 × 10(-3) mm(2)/s (95% CI 0.91-1.07). CONCLUSIONS: ADC values cannot be used to discriminate between molecular subtypes of BC.