Longitudinal wash-in slope changes on dynamic contrast enhancement MRI for predicting response to neoadjuvant chemotherapy in breast cancer.

Objectives: To determine whether wash-in slope (WIS) changes can predict pathologic complete response (pCR) following NAC in breast cancer.

Materials and methods: This single-center retrospective study included consecutive females with breast cancer who received NAC followed by surgery between January 2016 and December 2022. All patients received dynamic contrast-enhanced MRI (DCE-MRI) pretreatment, after 2 cycles, 4 cycles, and after completion of treatment. The percentage change in tumor WIS from that before treatment (ΔWIS) was measured at each time point. Predictive performance for pCR was assessed by using the area under the receiver operating characteristic curve (AUC) for the overall cohort and across molecular subtypes.

Results: A total of 162 patients were included in this study (mean age, 51.9 years ± 9.1 [SD]), and 43 (26.5%) achieved pCR. Overall, ΔWIS demonstrated comparable performance in predicting pCR after 2 cycles (AUC, 0.82; 95% CI: 0.73, 0.91), 4 cycles (AUC, 0.86; 95% CI: 0.78, 0.93), and after completion of NAC (AUC, 0.87; 95% CI: 0.8, 0.93), with no significant differences observed (all p > 0.05). Utilizing optimal threshold values of -33%, -44%, and -59% at each time point, ΔWIS yielded sensitivities ranging from 74.4% to 86.0% and specificities ranging from 75.6% to 80.7%. In molecular subtype analysis, ΔWIS after 4 cycles exhibited excellent predictive performance for pCR in triple-negative breast cancers (AUC, 0.96; 95% CI: 0.9, 1), outperforming its performance in Luminal B tumors (AUC, 0.83; 95% CI: 0.71, 0.94; p = 0.04).

Conclusion: Tumor WIS changes from DCE-MRI could dynamically monitor neoadjuvant chemotherapy (NAC).

Key points: Question Currently, there is no widely accepted standard imaging biomarker for predicting pCR in breast cancer patients undergoing NAC. Findings WIS changes outperformed tumor size in predicting pCR at four time points during NAC, and showed comparable predictive performance across all time points. Clinical relevance Longitudinal changes in the WIS derived from dynamic contrast-enhanced MRI enable real-time prediction of pathologic response to NAC in patients with breast cancer, supporting personalized treatment monitoring and decision-making.