Abstract: Background and purpose: While being recognized as a heterogeneous disease, triple-negative breast cancer (TNBC) is associated with aggressive biological property, a lack of targeted therapy and poor prognosis. Ultrasonography is one of the most important imaging methods for screening and differential diagnosis of TNBC. The sonographic features of TNBC show great variability. The primary objective of the present study was to evaluate the clinicopathological factors associated with sonographic appearances of invasive TNBC. Methods: With the ethical approval, 119 patients who were pathologically confirmed as having invasive TNBC were retrospectively reviewed for ultrasound, clinical and pathological data. Two ultrasound physicians with at least 5 years’ experiences for breast diseases reviewed all ultrasound images and evaluated the sonographic features which included orientation, shape, margin, internal echo pattern, posterior acoustic pattern and calcification. Patients were grouped according to age, tumor size, histological grade, Ki-67 proliferation level and human epidermal growth factor receptor-2 (HER2) score to investigate the effects of these factors on the ultrasonographic characteristics of TNBC. The effects of clinicopathological factors on the sonographic features of TNBC were studied. Results: The sonographic features of TNBC were associated with patient age, tumor size, histological grade, Ki-67 proliferation level and HER2 score. Age of patient affected the posterior acoustic pattern (P=0.002). Tumor size affected the presence of angular or spiculated margin (P=0.025). Histological grade affected tumor shape (P=0.008) and posterior acoustic pattern (P=0.044). Ki-67 level affected the tumor shape (P=0.042), presence of angular or spiculated margin (P=0.005) and posterior acoustic pattern (P=0.005). HER2 score affected the incidence of calcification inside TNBC (P=0.024). Conclusion: The sonographic features of TNBC are related to the patient’s age, tumor size, histological grade, Ki-67 proliferation level and HER2 score. Understanding the clinicopathological and immunohistochemical basis of sonographic characteristics and variability of TNBC is expected to assist early and accurate diagnosis of TNBC.

Key words: Triple-negative breast cancer, Ultrasonography, Pathology, Immunohistochemistry