# Association of residual ductal carcinoma in situ with breast cancer treatment outcomes after neoadjuvant chemotherapy according to hormone receptor status

## TL;DR

This study found that residual ductal carcinoma in situ after chemotherapy may increase the risk of distant metastasis in hormone receptor-negative breast cancer patients.

## Contribution

The study identifies a potential link between residual DCIS and worse outcomes in HR- breast cancer patients following neoadjuvant chemotherapy.

## Key findings

- Residual DCIS was found in 25.8% of patients who achieved pCR after neoadjuvant chemotherapy.
- HR- patients with residual DCIS had significantly worse distant metastasis-free survival compared to those without residual DCIS.
- Multivariate analysis showed residual DCIS in HR- patients was associated with an elevated risk of distant recurrence.

## Abstract

This research aimed to clarify the impact of residual ductal carcinoma in situ(DCIS) in surgical specimens obtained after neoadjuvant chemotherapy(NAC) for breast cancer on the associated prognosis outcomes.

This retrospective study was performed on a cohort of 1,009 patients who achieved pCR following NAC for breast cancer and underwent subsequent breast surgery at a single institution between January 2008 and December 2019. Overall survival, local recurrence-free survival, distant metastasis-free survival, and disease-free survival of the residual and non-residual DCIS groups were the outcomes compared, with further subgroup analysis performed according to hormone receptor status.

260 individuals (25.8%) presented with residual DCIS. Based on a median follow-up of 54.0 months, no significant differences in outcomes were observed between the two groups. Patients with residual DCIS and hormone receptor-negative (HR-) breast cancer demonstrated a significant decrease in distant metastasis-free survival (p = 0.030) compared to those without residual DCIS. In the HR + cohort, no significant difference was observed between the two groups. Multivariate analysis of the HR- cohort demonstrated a significant association between residual DCIS and an elevated risk for distant recurrence (hazard ratio = 2.3, 95% confidence interval = 1.01–5.20, p = 0.047).

Residual DCIS following NAC may impact breast cancer outcomes, particularly with respect to the occurrence of distant metastasis in HR- patients. Therefore, clinicians must vigilantly monitor patients with residual DCIS after NAC, and further research is needed to expand our understanding of the clinical implications of residual DCIS.

The online version contains supplementary material available at 10.1007/s12672-024-01157-z.