Abstracts

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E1217. Many Faces of Triple Negative Breast Cancer: Incidence, Diagnosis and Management
Authors
  1. Sally Woods; University of Cincinnati
  2. Rifat Wahab; University of Cincinnati
  3. Charmi Vijapura; University of Cincinnati
  4. Ann Brown; University of Cincinnati
  5. Su-Ju Lee; University of Cincinnati
  6. Mary Mahoney; University of Cincinnati
Background
Triple negative breast cancer (TNBC) accounts for 10-20% of all breast cancers in the US (1). TNBC is associated with a worse prognosis, high likelihood of recurrence, and greater risk of distant metastasis (1 2). There is a higher incidence of TNBC in premenopausal African American (AA) women and BRCA1 carriers (2 3 4). Not only can TNBC have benign imaging features, it is also more commonly seen in younger women, which can lead to delayed diagnosis.

Educational Goals / Teaching Points
The exhibit objectives are to describe the prevalence, risk factors, and affected patient populations for TNBC, familiarize radiologists with the variable imaging findings of TNBC to improve diagnosis, review imaging techniques that may identify TNBC, and review updated management guidelines of TNBC.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
On mammography, some studies report TNBC presents as a round or oval high-density mass with circumscribed or microlobulated margins as the most common finding (60%) while others report an irregular mass (49-69%) with spiculated, obscured, or indistinct margins as the most common finding (54-67%) (2 4 6). Studies generally agree that TNBC less commonly presents as a mass with calcifications (21-30%), and rarely as calcifications alone (7%)(3 6). On ultrasound, TNBC frequently presents as a hypoechoic mass with microlobulated or angular margins (6), but can present as a mass with circumscribed margins and posterior acoustic enhancement (2 4). This presentation may be mistakenly interpreted as a benign mass. The pathophysiology of the smooth borders is hypothesized to represent the rapidly proliferating tumor with pushing borders resulting in circumscribed margins prior to stromal reaction (8). On MRI, TNBC typically presents with smooth margins, persistent kinetics, rim enhancement, and/or high T2 signal which are features that overlap with benign masses (7 8). Heterogeneity of imaging features can correlate with pathological grade, Ki67 proliferation level, HER2 score, and AR status of TNBC (1 9). Calcifications have also been associated with a higher HER2 score; therefore, TNBC less often presents with calcifications (1). Systemic chemotherapy is the first line treatment for TNBC. Patients are typically given neoadjuvant chemotherapy to decrease tumor size and may continue with adjuvant therapy to decrease the risk of recurrence (10). Molecular targeted therapies were recently approved to treat advanced TNBC and include PARP inhibitors and the checkpoint inhibitor, atezolizumab (10 11). Improved response rates have been seen with checkpoint inhibitors and chemotherapy as first line therapy.

Conclusion
TNBC is an aggressive tumor with a poor prognosis. Imaging features are variable and may relate to the underlying tumor pathology and biomarkers. Radiologists should be aware that TNBC can have a benign imaging appearance and should maintain a high index of suspicion, especially when evaluating premenopausal AA females and BRCA1 carriers, who have a higher incidence of TNBC. Imaging appearance and biomarkers may predict response to chemotherapy, which is the mainstay of TNBC treatment.