# 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

## TL;DR

This study suggests that changes in background breast tissue enhancement on MRI after chemotherapy may predict recurrence risk in triple-negative breast cancer patients.

## Contribution

The study identifies contralateral BPE changes as a novel predictive factor for disease-free survival in TNBC patients.

## Key findings

- Post-NAC BPE was significantly associated with disease-free survival in a multivariate Cox model.
- Patients with BPE changing from high to low had a lower recurrence rate than those changing from low to high.
- BPE levels were linked to ADC values and menopausal status after neoadjuvant therapy.

## Abstract

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) is unclear.

Between March 2017 and June 2019, 76 TNBC patients undergoing neoadjuvant therapy and subsequent surgery were included in the study. 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).

The mean age was 51.29 ± 9.53 years; 46 (60.5%) patients achieved pathological complete response (pCR), and 13 (17.1%) patients developed recurrence, with a median follow-up of 80 months (interquartile range: 64, 90). 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: HR = 1), along with multifocality on post-NAC MRI (HR = 3.65, no multifocality: HR = 1) and pCR (HR = 7.27, pCR: HR = 1).

Contralateral BPE and its change after neoadjuvant chemotherapy may reflect the recurrence risk in triple-negative breast cancer patients.