# Clinicopathological characteristics and prognostic factors of invasive micropapillary carcinoma of the breast

## TL;DR

This study identifies factors influencing recurrence and metastasis in breast invasive micropapillary carcinoma, emphasizing the importance of tumor size, lymph node status, histologic grade, and chemotherapy.

## Contribution

The study provides new insights into prognostic factors for breast IMPC, offering guidance for risk stratification and clinical monitoring.

## Key findings

- Breast IMPC has a 5-year recurrence and metastasis-free survival rate of 86.0%.
- Tumor size ≤1.7 cm, lower lymph node positivity, and histologic grade I-II are associated with better outcomes.
- Neoadjuvant chemotherapy significantly improves prognosis in breast IMPC patients.

## Abstract

To evaluate the clinicopathological characteristics of breast invasive micropapillary carcinoma (IMPC) and identify factors associated with recurrence and metastasis.

The study retrospectively analyzed 401 cases of breast IMPC diagnosed between 2017 and 2021. The primary endpoint was recurrence and metastasis–free survival (RMFS). Secondary endpoints included locoregional recurrence–free survival (LRRFS) and distant metastasis–free survival (DMFS). Survival was estimated using the Kaplan–Meier method and compared with the log-rank test. Univariable and multivariable Cox regression analyses were performed to identify prognostic factors. Continuous variables were categorized using maximum log-rank statistics to optimize group stratification.

The median follow-up duration was 46.9 months (range, 1–92 months). The 5-year RMFS, LRRFS and DMFS rates were 86.0% (95% CI, 82.2%-90.0%), 97.5% (95% CI, 95.8%-99.3%) and 86.5% (95% CI, 82.8%-90.5%), respectively. Multivariable Cox analysis showed that maximum tumor diameter (≤ 1.7 cm vs. >1.7 cm, P = 0.018), the log odds of positive lymph nodes (LODDS) (≤ 0 vs. >0, P = 0.008), histological grade (I-II vs. III, P = 0.002), and receipt of neoadjuvant chemotherapy (P = 0.003) were independent predictors of recurrence and metastasis.

Breast IMPC carries a relatively high risk of recurrence and metastasis. Tumor size, LODDS, histologic grade, and neoadjuvant chemotherapy were independently associated with outcomes, underscoring the need for closer clinical monitoring and refined risk stratification in this subtype.

The online version contains supplementary material available at 10.1007/s12672-025-04287-0.