Axillary sentinel node and tumour-related factors associated with non-sentinel node involvement in breast cancer

Background: After completion of axillary dissection, many breast cancer patients with axillary sentinel nodal involvement are found to have regional disease limited to the sentinel nodes. These patients are exposed to the morbidity of axillary clearance without any expected therapeutic benefit. Methods: Sentinel node biopsy was performed either with Patent blue dye or with a combined dye, radiocolloid and gamma-probe-guided method involving peritumoral tracer administration. For a series of 150 consecutive patients with involved axillary sentinel nodes and axillary dissection, factors associated with non-sentinel nodal involvement were analysed in a multivariate analysis based on logistic regression with the use of fractional polynomials. Results: The following variables were found to be potentially associated with non-sentinel node metastases: tumour size, sentinel node metastasis size, number of examined sentinel nodes, percentage of involved sentinel nodes (the latter two were found to be significant only when in combination), and extracapsular perinodal spread. Conclusions: Isolated tumour cells and micrometastases in axillary sentinel nodes carry a low risk of non-sentinel node metastasis. The risk of metastasis to further echelon nodes is higher with macrometastases, especially if there is extracapsular growth and the proportion of involved sentinel nodes is high.