Preoperative focal breast edema on T2-weighted MRI as a predictor of sentinel lymph node metastasis in clinically node-negative T1-2 breast cancer: A retrospective bicentric study.

PURPOSE

To investigate the predictive value of breast edema identified on preoperative T2-weighted MRI for sentinel lymph node (SLN) metastasis in patients with clinically node-negative (cN0) T1 and T2 stage invasive breast cancer.

METHODS

In this retrospective bicentric study, women with cN0 invasive breast cancer- confirmed by clinical examination, ultrasound, and MRI- who underwent preoperative breast MRI between January 2016 and December 2019 at two independent institutions were included. Breast edema on T2-weighted images was assessed. Univariate and multivariate logistic regression analyses were performed to identify independent predictors of SLN metastasis. The area under the receiver operating characteristic curve (AUC) and negative predictive value (NPV) were calculated.

RESULTS

Of the 381 patients, SLN metastasis was observed in 67 of 267 patients (25.1 %) in the primary cohort and in 24 of 114 patients (21.1 %) in the validation cohort. Breast edema was independently associated with SLN metastasis in both cohorts. A model based solely on breast edema achieved an AUC of 0.738 (95 % CI: 0.667-0.809) and an NPV of 89 % in the primary cohort, with consistent performance in the validation cohort. Compared with a model using only clinicopathological features (age and molecular subtype), the combined model incorporating breast edema significantly improved predictive performance (AUC: 0.822 vs. 0.654, p < 0.001; NPV: 92 % vs. 83 %), which was confirmed in the validation cohort (AUC: 0.793 vs. 0.616, p = 0.021; NPV: 92 % vs. 88 %).

CONCLUSION

Breast edema is independently associated with SLN metastasis. Breast edema combing with clinical-pathological features may help identify patients at lower risk of SLN metastasis, potentially aiding in SLNB omission decisions.