Prediction of tumour involvement in remaining axillary lymph nodes when the sentinel node in a woman with breast cancer contains metastases

Background: In a significant proportion of women with breast cancer, the sentinel node is the only involved node in the a,axilla. The purpose of this study was to identify factors associated with histologically positive non-sentinel lymph nodes. Methods: Between 1997 and 2002, 800 women with early breast cancer underwent sentinel node biopsy. In 263 patients the node contained metastases, including 83 with micrometastases detected by immunohistochemistry (IHC), 40 micrometastases detected on haematoxylin, eosin and safranine (RES) staining, and 140 macrometastases. All clinical and histological criteria were recorded and analysed with reference to histology of the non-sentinel node. Results: The risk of metastasis in the non-sentinel lymph node was related to the volume of the turnout in the sentinel node. Non-sentinel nodes were involved in five (6.0 per cent) of 83 women when the sentinel node contained only micrometastatic cells detected on IHC, and in three (7.5 per cent) of 40 women when micrometastases were detected by HES, compared with 5 5 (39.3 per cent) of 140 when the sentinel node contained macrometastases on HES staining. Univariate analysis revealed a significant association between non-sentinel node involvement and type of metastasis within the sentinel node, clinical primary turnout size, palpable axillary lymph nodes before operation, pathological primary tumour size and the presence of peritumoral lymphovascular invasion. On multivariate analysis, the type of metastasis within the sentinel node (P < 0.001), histological tumour size greater than 20 mm (P = 0.017) and the presence of palpable axillary nodes before operation (P = 0.014) remained significant. Conclusion: Clinical and pathological factors associated with sentinel node histology can reliably predict women for whom further axillary clearance is recommended, but it is not yet possible to determine a subgroup of patients in whom the sentinel node is the only involved node and for whom further axillary treatment may be unnecessary.