# Correlations Between Mammographic Breast Density and Outcomes After Neoadjuvant Chemotherapy in Patients with Locally Advanced Breast Cancer

## TL;DR

High breast density in obese women may reduce the effectiveness of chemotherapy for breast cancer, leading to worse outcomes.

## Contribution

The study reveals that the combination of obesity and high mammographic breast density is linked to poorer chemotherapy outcomes in breast cancer patients.

## Key findings

- Obese patients with dense breasts had 0% tumor elimination compared to 28% in non-dense breasts.
- Obese patients with dense breasts had doubled cancer recurrence and death rates.
- Non-obese patients showed no significant differences based on breast density.

## Abstract

This study investigates whether the amount of dense breast tissue on the mammograms of patients with early breast cancer affects how well chemotherapy given before surgery shrinks their cancer and whether they survive their cancer. We measured mammographic breast density along with the rate of disappearance of cancer for the time of surgery, cancer return rates and survival in 127 women undergoing chemotherapy before surgery for early breast cancer. In the whole patient group, no significant differences were seen. However, when we looked at the effects of weight, obese patients with dense breasts had worse outcomes than obese patients with non-dense breasts; no tumours were microscopically eliminated versus 28%, and rates of cancer return and deaths doubled. Non-obese patients showed no such pattern. These findings suggest that breast density and high body weight together may hinder chemotherapy success, and that research on better treatments for these patients is needed.

Introduction: An inverse association between high mammographic breast density (MBD) and pathologic complete response (pCR) following neoadjuvant chemotherapy (NAC) for early breast cancer (EBC) has been reported. However, the relationship of MBD to relapse-free (RFS) and breast cancer-specific survival (BCSS) is unexplored. This study aims to validate the relationship between MBD and NAC pCR in EBC and to assess correlations with RFS and BCSS. Materials & Methods: MBD was measured on contralateral mammograms in 127 women before NAC using Cumulus software. The percent dense area was correlated with patient and tumour characteristics, pCR, RFS and BCSS. Results: Mean MBD was higher in relapsing patients (p = 0.041) but did not vary by pCR or BC-deaths. As a dichotomous variable, no difference was seen between high and low MBD cohorts for pCR (17.5 vs. 25.0%, p = 0.15), BC relapse (38 vs. 30%, p = 0.15) or BC death (32 vs. 25%, p = 0.20). A planned analysis by body mass index (BMI) demonstrated high MBD associated with lower pCR (0% vs. 28.1%, p = 0.036) and trends for higher relapse (56% vs. 28%, p = 0.063) and BC deaths (56 vs. 28%, (p = 0.071)) in obese patients. No relationship was observed in non-obese patients. Conclusions: Obesity and high MBD may interact to cause chemoresistance. Further research in these patients is warranted.