Background Parenchymal Enhancement of the Contralateral Breast on Preoperative Contrast-Enhanced Breast MRI as a Potential Predictive Factor for Disease-Free Survival in Triple-Negative Breast Cancer Patients

Xiao-Ting LiXing WangHai-Tao ZhuNan SunHai-Bin Hai-bin ZhuLiang YouXiao-Lei GuYao LuoZhao-Qing Fan^*Ying-Shi Sun^*

• Beijing Cancer Hospital, Peking University, Beijing, China

Background Background parenchymal enhancement (BPE) observed on dynamic contrast-enhanced (DCE) MRI of the contralateral breast is considered to be associated with survival outcomes. However, the prognostic significance of BPE in triple-negative breast cancer (TNBC) was unclear. Methods Between March 2017 and June 2019, 76 TNBC patients undergoing neoadjuvant therapy and subsequent surgery were included. All patients underwent DCE-MRI before and after neoadjuvant therapy. Radiologists graded BPE as minimum, mild, moderate, and marked. The BPE level was analyzed according to clinicopathological characteristics and MRI findings. Survival analysis was conducted for clinicopathological characteristics and MRI findings according to disease-free survival(DFS). Results The mean age was 51.29±9.53 years; 46(60.5%) patients achieved pathological complete response(pCR); 13(17.1%) patients developed recurrence, with a median follow-up of 80 months(interquartile range:64, 90). The dichotomous BPE (minimal/mild vs moderate/marked) on post-NAC MRI was statistically associated with post-NAC ADC and menopausal status. Patients with BPE changing from high to low level demonstrated statistically lower recurrence rate than patients with BPE changing from low to high(P=0.022). BPE on post-NAC MRI was in the final multivariate cox model for DFS(HR=6.57, minimal/mild as HR=1), along with multifocality on post-NAC MRI(HR=3.65, no multifocality as HR=1) and pCR(HR=7.27, pCR as HR=1). Conclusions Contralateral BPE and its change after neoadjuvant chemotherapy may reflect the recurrence risk in triple-negative breast cancer patients.