# Impact of breast tumor size discrepancy between contrast-enhanced and conventional ultrasonography on axillary node metastasis: a retrospective cohort study

## TL;DR

This study found that a larger tumor size on contrast-enhanced ultrasound compared to conventional ultrasound is linked to higher axillary lymph node metastasis and worse prognosis in breast cancer.

## Contribution

The study identifies tumor size discrepancy between CEUS and cUS as a novel predictor of axillary node metastasis in breast cancer.

## Key findings

- A tumor size discrepancy of ≥4.0 mm on CEUS was significantly associated with axillary lymph node metastasis.
- The DISCR group had a 5.8-fold higher risk of ALN metastasis compared to the non-DISCR group.
- The DISCR group showed lower 5-year recurrence-free survival rates than the non-DISCR group.

## Abstract

Conventional ultrasonography (cUS) and contrast-enhanced ultrasonography (CEUS) are used to evaluate breast cancer tumors and axillary lymph nodes (ALN), by which the treatment strategy for breast cancer is determined. A breast tumor size discrepancy on CEUS compared with cUS is often observed, for which the reasons are unclear. We hypothesized that this discrepancy reflects the metastatic potential, and this study investigated the association between size discrepancies on cUS and CEUS in relation to ALN metastasis in breast cancer.

This retrospective study enrolled 259 patients who underwent surgery for breast cancer after preoperative cUS and CEUS examinations. Patients were grouped into a DISCR (i.e., tumor size discrepancy ≥ 4.0 mm between CEUS and cUS measurements) and non-DISCR group. The primary outcome was ALN metastasis, defined by pathological evaluation. Secondary outcomes were the 5-year recurrence-free survival rates.

There were 94 patients in the DISCR and 165 in the non-DISCR groups. No tumor size differences measured by cUS were observed between two groups (p = 0.82), whereas the DISCR group had a significantly higher rate of ALN metastasis (p < 0.01). Multivariate analyses showed a discrepancy of ≥ 4.0 mm was a risk for ALN metastasis (odds ratio: 5.838, 95% confidence interval [CI]: 2.408–14.155). The 5-year recurrence-free survival rate was lower in the DISCR (0.750, 95% CI: 0.632–0.868) than in the non-DISCR (0.924, 95% CI; 0.870–0.978) group.

An increase in contrast-enhanced ultrasonography tumor size is helpful for assessing axillary lymph node metastasis and prognosis.

The online version contains supplementary material available at 10.1186/s12885-025-15167-9.