Detectability and clinicohistological characteristics of small (≤1 cm) invasive breast cancer

Abstract

Purpose: To investigate the detectability and imaging characteristics of primary tumors according to imaging modalities and to identify clinical features and histological prognostic factors for axillary metastases in patients with small (≤1cm, T1a and T1b) invasive breast cancer.

Materials and methods: A total of 221 patients with histologically confirmed small invasive cancers were included for the statistical analysis. At mammography, ultrasonography and MRI, the detectability, and imaging characteristics of primary tumors were compared in patients with or without axillary metastases. Clinical features and histological prognostic factors for axillary metastases were investigated.

Results: Of 221 patients examined, axillary metastasis was found in 42 (19%) at the time of surgery. There was no significant difference in detectability of small tumors using ultrasonography and MRI between patients with and without axillary metastasis. However, mammography had a higher positive rate of primary tumors in patients with axillary metastasis than without metastasis (92.9% vs. 77.1%, p=0.023). Patients with axillary metastasis in small cancers showed more common architectural distortion than negative (p=0.0147) or mass (p=0.0356) on mammography. Clinical features were not different in the two groups. Only lymphovascular invasion was independently associated with axillary metastasis (p=0.0051, 95% CI, 1.527-11.597).

Conclusion: The detectability of small invasive breast cancers among patients with and without axillary metastasis is different with mammography, but not with US and MRI. Lymphovascular invasion is only a predictor for axillary metastasis in small invasive cancers.

Keywords: Axillary lymph node metastasis; Breast cancer; Diagnostic modality; Magnetic resonance imaging; Mammography; Ultrasonography.