Apparent diffusion coefficient as a potential non-invasive predictor of histological grade of breast cancer

Aim: This study aimed to explore the association between the apparent diffusion coefficient (ADC) of the breast tumor and the histological grade of breast cancer. Methods: We retrospectively selected patients with breast cancer and breast magnetic resonance imaging (MRI) performed on a 1.5T system. We obtained the ADC of the breast tumor, and the histological grade of breast cancer was used as the reference standard. We compared the mean ADC between the histological grades and performed a linear regression analysis to explore the association of the histological grade and the ADC value. Results: A total of 47 patients with breast cancer were evaluated, four with histological grade 1, 22 with grade 2, and 21 with grade 3. The mean ADC of the histological grade 3 tumors was significantly lower than that of the grade 2 tumors (0.95 x 10-3mm2/s vs. 1.12 x 10-3mm2/s, p= 0.020). In a subpopulation that included tumors with histological grades 2 and 3, we found that histological grade significantly predicts the ADC value (p = 0.02). Conclusions: Tumor ADC is a potential non-invasive predictor of the histological grade of breast cancer, specifically for grades 2 and 3. Tumor ADC can be an adjunct in the personalization of imaging surveillance of patients with breast cancer. To our knowledge, this is the first study in which a predictive association between histological grade and tumor ADC has been studied in breast cancer in Latin American women.