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 featuresand a poor clinical outcome. Therefore, early detection of TNBC without missed diagnosis is a requirementto improve prognosis. Preoperative ultrasound features of TNBC may potentially assist in early diagnosis ascharacteristics of disease. Purpose: To retrospectively evaluate the sonographic features of TNBC compared toER (+) cancers which include HER(-) and HER2 (+), and HER2 (+) cancers which are ER (-). Materials and
Methods: From June 2012 through June 2014, sonographic features of 321 surgically confirmed ER (+) cancers(n=214), HER2 (+) cancers (n=66), and TNBC (n=41) were retrospectively reviewed by two ultrasound specialistsin consensus. The preoperative ultrasound and clinicopathological features were compared between the threesubtypes. In addition, all cases were analyzed using morphologic criteria of the ACR BI-RADS lexicon.
Results:Ultrasonographically, TNBC presented as microlobulated nodules without microcalcification (p=0.034). A lowerincidence of ductal carcinoma in situ (p<0.001), invasive tumor size that is>2 cm (p=0.011) and BI-RADS category4 (p<0.001) were significantly associated with TNBC. With regard to morphologic features of 41 TNBC cases,ultrasonographically were most likely to be masses with irregular (70.7%) microlobulated shape (48.8%), becircumscribed (17.1%) or have indistinct margins (17.1%) and parallel orientation (68.9%). Especially TNBCmicrolobulated mass margins were more more frequent than with ER (+) (2.0%) and HER2 (+) (4.8%) cancers.
Conclusions: TNBC have specific characteristic in sonograms. Ultrasonography may be useful to avoid misseddiagnosis and false-negative cases of TNBC.