Qualitative shear wave elastography in malignant breast lesions: predictive factors associated with false-negative findings and their biological characteristics.

BACKGROUND: Shear wave elastography (SWE) complements B-mode ultrasound (BMUS) for breast lesion characterization. However, malignant breast lesions that exhibit false-negative findings on qualitative SWE lack the expected increase in stiffness, which may contribute to missed diagnosis and underestimation of disease severity. This study aimed to identify the BMUS characteristics and clinicopathologic predictors associated with false-negative findings on qualitative SWE in malignant breast lesions, and to characterize the tumor biological behavior of these false-negative lesions, including axillary lymph node (ALN) status, histologic grade, and molecular subtype. METHODS: A total of 770 patients (with 770 malignant breast lesions) were enrolled in the study between March 2019 and August 2024. All patients underwent preoperative BMUS and SWE examinations. A multivariate logistic regression analysis was conducted to identify the predictive factors associated with false-negative SWE findings. The biological behaviors of these false-negative lesions were analyzed based on the final surgical pathology results. RESULTS: Among the 770 malignant breast lesions, 703 (91.3%) were classified as true-positive findings on SWE, and 67 (8.7%) were classified as false-negative findings on SWE. Multivariate regression analysis revealed that a maximum lesion size <20 mm (95% confidence interval (CI): 3.105-11.520; P<0.001), a circumscribed margin (95% CI: 1.522-4.763; P=0.001), and ductal carcinoma in situ (DCIS) (95% CI: 4.715-18.057; P<0.001) were significantly associated with false-negative SWE findings. Of the 67 false-negative lesions, 32 (47.8%) were diagnosed as DCIS, and 35 (52.2%) were diagnosed as invasive carcinomas. All the breast cancer patients exhibited a low ALN burden. Moreover, among the 35 invasive carcinomas, 85.7% (30/35) were the luminal A or luminal B subtype. CONCLUSIONS: A maximum breast lesion size <20 mm, a circumscribed margin, and DCIS were identified as significant predictors of false-negative SWE findings. False-negative SWE findings were associated with tumors exhibiting low invasive biological potential and lower-risk pathological profiles, including a low ALN burden, a higher proportion of DCIS, and a predominance of Luminal A and Luminal B subtypes.