Multimodal Visual Phenotypes as a Reflection of the Biology of the Main Molecular Subtypes of Stage T1 Breast Cancer

Introduction . Breast cancer (BC) molecular subtypes differ not only in prognosis and response to systemic therapy, but also in morphological features that determine imaging appearance. A comprehensive assessment of digital mammography and ultrasound findings may reflect tumor biology and provide additional information about the probable molecular subtype at the stage of primary imaging. The purpose of the study is to identify multimodal visual phenotypes of luminal HER2‑negative, HER2‑positive, and triple-negative stage T1 BC based on the integrated assessment of digital mammography and ultrasound findings. Materials and methods . This multicenter retrospective cross-sectional study was based on archived medical records of 345 patients with morphologically verified invasive stage T1 BC. Digital mammography, breast ultrasound with color Doppler mapping and strain elastography, and morphological and immunohistochemical examinations had been performed as part of routine medical care before the data were included in the analysis. According to the immunohistochemical profile, the records were assigned to three groups: luminal HER2‑negative BC (n = 215), HER2‑ positive BC (n = 74), and triple-negative BC (n = 56). Results . Luminal HER2‑negative BC was characterized by a hyperdense mass with spiculated margins, posterior acoustic shadowing, predominantly peripheral vascularity, and high tissue stiffness. HER2‑positive BC showed a higher frequency of pleomorphic microcalcifications with linear or segmental distribution and frequent visualization of calcifications on ultrasound. Triple-negative BC was characterized by the absence of microcalcifications, posterior acoustic enhancement, mixed or intranodular vascularity, and a predominance of Tsukuba elasticity score 5. Conclusion . The main molecular subtypes of stage T1 BC demonstrate stable multimodal visual phenotypes. Integrated interpretation of mammographic and ultrasound features may serve as an additional tool for preoperative assessment of tumor biological characteristics.