ABSTRACT

The sentinel lymph node biopsy for breast cancer allows for accurate staging of the axilla while the axillary node dissection can be avoided in patients with no sentinel node metastasis. However the sentinel lymph node is the only focus of axillary metastasis in a significant proportion of patients. The purpose of this study is to determine if a completion axillary dissection is necessary when microscopic metastasis is detected in the sentinel lymph node (SLN) of patients diagnosed with breast cancer.

We reviewed the records of 425 patients with invasive breast cancer who underwent SLN biopsy at our institution between October 1998 and March 2005. These patients underwent intraoperative lymphatic mapping with blue dye alone or in combination with technetium-labeled sulfur colloid.

Sentinel nodes were identified in 409/425 of the patients (96%). Of the 409 patients in whom SLN biopsy was successful, 161 (39%) had metastasis in the SLN, and a completion axillary dissection was performed. Seventy-nine of these 139 patients (57%) with macrometastasis had additional disease in the axilla. A total of 22 patients was determined to have micrometastasis and 3 of 22 them (14%) had metastasis in non-sentinel lymph node(s) (p<0.0001). Multivariate analysis revealed that primary tumor >2cm (p=0.004), the presence of macrometastases (p=0.008) and extracapsular invasion (p=0.041) were independent predictors of positive non-SLNs.

The likelihood of positive non-SLNs correlates with primary tumor size, size of the SLN metastasis, and extracapsular lymph node extention. The analysis of these factors may help determine which patients would benefit from additional axillary surgery. Especially axillary dissection may not be necessary for the subset of breast cancer patients with micrometastasis detected upon SLN biopsy.