Predictors of axillary lymph node metastases in patients with invasive breast carcinoma by a combination of classical and biological prognostic factors

The presence of axillary lymph node metastases (ALNMs) is the most importan t prognostic factor in breast carcinoma. If ALNMs were predictable without performing axillary lymph node dissection (ALND), this procedure would not be necessary in selected patients. Using a combination of some of the new b iological markers with the classical ones, our objective was I) to identify the best set of predictors of ALNMs, and II) to define predictive models w ith either high or low probability of ALNMs. We studied 102 patients with i nvasive breast carcinoma. All patients underwent ALND, and at least 10 axil lary lymph nodes per case were obtained. In the primary tumour we evaluated size, histological subtype and grade, lymphatic/vascular invasion and marg in. Hormone receptor status, MIB1 index, microvessel density, c-erbB-2 and cathepsin D expression were assessed by immunohistochemistry, and DNA ploid y and S-phase by flow cytometry. Risk factors for ALNMs were estimated by n onlinear logistic regression analysis. The best predictors of ALNMs were: t umour size > 2 cm [OR 6.45, 95% confidence interval (CI) 21.74 to 1.91], pr esence of lymphatic/ vascular invasion [OR 4.95, CI (14.50 to 1.69)], infil trative margin [OR 9.87 CI (37.44 to 2.60)] and high MIB-1 index [OR 8.39, CI (33.47 to 2.10)]. Two subsets had a very high risk of ALNMs: I) tumour s ize > 2 cm, with lymphatic/ vascular invasion and infiltrative margin; 26 ( 89.66%) of 29 patients of this subgroup had ALNMs, and (II) tumour size :> 2 cm, with lymphatic/vascular and high MIBI index.; eight of the nine (89%) patients of this subgroup had ALNMs. We could also identify a two-variable model with a very low risk of ALNMs constituted by tumour with circumscrib ed margin and low 11 MIB-1 index. Of the 19 patients showing these features , only 1 (5.26%) had ALNMs. Therefore, pathological features of the primary tumour can help to assess the risk for ALNM in invasive breast carcinoma. Such risk assessment might avoid regional surgical overtreatment.