Mammographic and ultrasonographic features of triple-negative breast cancer: a comparison with other breast cancer subtypes

Background: Triple-negative breast cancer (TNBC) is known to be associated with aggressive biologic features and a poor clinical outcome. Therefore, early detection of TNBC without missing cancer is mandatory to improve prognosis. Purpose: To retrospectively evaluate the mammographic and sonographic features of TNBC compared to ER (+) cancers and HER2 (+) cancers. Material and Methods: From June 2011 through June 2012, mammographic and sonographic features of 281 surgically confirmed ER (+) cancers (n = 153), HER2 (+) cancers (n = 83), and TNBC (n = 45) were retrospectively reviewed by two radiologists in consensus. The clinicopathological features were also compared between the three subtypes. Additionally the 45 TNBC cases were analyzed using morphologic criteria of ACR BI-RADS lexicon. Results: Most TNBC (93.3%, 42 of 45) were mammographically seen and presented with mass or focal asymmetry without microcalcifications (P < 0.001). Ultrasonographically TNBC were presented as hypoechoic nodule without microcalcifications (P < 0.001). Palpable symptom (P < 0.001), a lower incidence of ductal carcinoma in situ (P < 0.001), invasive tumor size that is >2 cm (P < 0.028) and high histologic grade (P < 0.001) were significantly associated with TNBC. With regard to morphologic features of 45 TNBC cases, TNBC were most likely to be hyperdense mass (89.3%) with oval (68.9%) or lobular shape (28.6%) and indistinct (42.9%) or circumscribed margin (32.1%) on mammogram. Ultrasonographically TNBC were most likely to be a hypoechoic mass (82.2%) with irregular (68.9%) or oval (28.9%) shape and microlobulated (46.7%), circumscribed (17.8%) or indistinct margin (17.8%) and parallel orientation (68.9%). Conclusion: Being familiar with combined mammographic and ultrasonographic features of TNBC may be useful to avoid false-negative cases of TNBC.