Aim: nodal metastatic involvement is the most important prognostic indicator in breast cancer. Sentinel node biopsy led to an increase in the detection of micrometastases. The aim of our analysis was to identify predictive factors of micrometastases and macrometastases of sentinel node.

Materials and Methods: between January 2000 and December 2006, 675 patients were treated with breast surgery and sentinel node evaluation at University of Florence (Florence, Italy). Estrogen receptor status, progesterone receptor status, and Ki-67 labeling index determined with the MIB1 monoclonal antibody were assessed. HER2 immunohistochemistry (IHC) expression was scored as follows: 0, no staining or faint membrane staining; 1+, faint membrane staining in >10% of tumor cells, incomplete membrane staining; 2+, weak to moderate membrane staining in >10% of tumor cells; and 3+, intense circumferential membrane staining in >10% of tumor cells. HER2 scores of 0 and 1+ were considered negative. HER2 IHC 3+ and fluorescent in situ hybridization (FISH) – amplified tumors were considered positive. All IHC 2+ tumors and indeterminate tumors were tested for gene amplification by FISH. The sentinel node was examined by hematoxylin and eosin. The patients were divided into three groups based on AJCC TNM staging: sentinel node negative (n = 601); micrometastases if tumor deposit more than 0.2 mm but <2 mm (n = 20), and macrometastases if tumor deposit more than 2 mm (n = 53).

Results: at the logistic regression with polytomous analyses (outcome micrometastases or macrometastases), age (p = 0.048), menopausal state (p = 0.013), breast quadrant (p = 0.005), lymph vascular invasion (p = 0.0001), post-surgical T stage (p = 0.0001), histotypes (p = 0.023), HER2 status (p = 0.02), Ki-67 proliferative index (p = 0.001) and nuclear grade (p = 0.024) were significantly correlated with sentinel node macrometastases. Sentinel node biopsy technique (cytological aspiration versus histological biopsy) was not associated with micrometastases (p = 0.89) or macrometastases (p = 0.48) occurrence. The only feature significantly associated with micrometastases in sentinel node was the lymph vascular invasion (p = 0.0001).

Conclusion: the presence of micrometastases remained fairly constant over time if compared to macrometastases. In our experience the only feature significantly associated with micrometastases in sentinel node is the lymph vascular invasion.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-01-25.