Abstract:Objective To construct a breast cancer risk regression equation based on multimodal ultrasound and multivariable analysis.Methods The clinical data of 150 patients with breast nodules treated at Bijie Hospital of Zhejiang Provincial People's Hospital between August 2023 and December 2024 were retrospectively analyzed. According to lesion type, the patients were divided into an observation group (breast cancer, n = 52) and a control group (benign breast lesions, n = 98). All patients underwent multimodal ultrasonography. A Lasso-logistic multivariable model was used to analyze factors associated with breast cancer, construct a risk regression equation, and evaluate its predictive value for differentiating malignant from benign breast lesions.Results The observation group had higher proportions of indistinct mass margins, heterogeneous mixed echogenicity, spiculation, malignant contrast-enhanced ultrasound (CEUS) findings, and grade II superb microvascular imaging (SMI) blood flow, as well as higher E-mean, E-max, carbohydrate antigen 15-3 (CA15-3), and carcinoembryonic antigen levels, than the control group (P < 0.05). Multivariable logistic regression showed that spiculation [O^R = 3.682 (95% CI: 1.274, 10.641) ], higher E-mean [O^R = 4.128 (95% CI: 2.617, 6.511) ], malignant CEUS findings [O^R = 5.831 (95% CI: 3.645, 9.328) ], grade III SMI blood flow [O^R = 3.225 (95% CI: 1.239, 8.394) ], and higher CA15-3 [O^R = 7.819 (95% CI: 1.073, 56.977) ] were risk factors for breast cancer (P < 0.05). The resulting equation was Logit(P) = 2.112 + 1.303 × spiculation + 1.418 × E-mean + 1.763 × CEUS findings + 1.171 × SMI blood flow grade + 2.057 × CA15-3. The equation had an area under the receiver operating characteristic curve of 0.901, a sensitivity of 82.7% (95% CI: 0.753, 0.914), and a specificity of 76.5% (95% CI: 0.683, 0.847) for determining the nature of breast lesions.Conclusion Breast cancer is associated with spiculation, E-mean, CEUS findings, SMI blood flow grade, and CA15-3 level. A risk regression equation based on these factors may facilitate breast cancer screening.