The risk of nodal metastases in breast cancer patients with clinically negative lymph nodes: a population-based analysis

A population-based study was performed to assess the likelihood of axillary lymph node metastases in patients with clinically negative lymph nodes, ac cording to patient age, tumor size and site, estrogen receptor status, hist ologic type and mode of detection. Data were obtained from the population-b ased Eindhoven Cancer Registry. During the period 1984-1997, 7680 patients with invasive breast cancer were documented, 6663 of whom underwent axillar y dissection. Of the 5125 patients who were known to have clinically negati ve lymph nodes and underwent axillary dissection, 1748 (34%) had positive l ymph nodes at pathological examination. After multivariate analysis, histol ogic type, tumor size, tumor site and the number of lymph nodes in the axil lary specimen remained as independent predictors of the risk of nodal invol vement (P < 0.001). Lower risks were found for patients with medullary or t ubular carcinoma, smaller tumors, a tumor in the medial part of the breast and patients with less than 16 nodes examined. This study gives reliable es timates of the risk of finding positive lymph nodes in patients with a clin ically negative axilla. Such information is useful when considering the nee d for axillary dissection and to predict the risk of a false-negative resul t when performing sentinel lymph nodebiopsy.