Meta-analysis of predictive factors for non-sentinel lymph node metastases in breast cancer patients with a positive SLN

Aims: A meta-analysis was performed to identify the clinicopathological variables most predictive of non-sentinel node (NSN) metastases when the sentinel node is positive. Methods: A Medline search was conducted that ultimately identified 56 candidate studies. Original data were abstracted from each study and used to calculate odds ratios. The random-effects model was used to combine odds ratios to determine the strength of the associations. Findings: The 8 individual characteristics found to be significantly associated with the highest likelihood (odds ratio > 2) of NSN metastases are SLN metastases > 2 mm in size, extracapsular extension in the SLN, > 1 positive SLN, <= 1 negative SLN, tumour size > 2 cm, ratio of positive sentinel nodes > 50% and lymphovascular invasion in the primary tumour. The histological method of detection, which is associated with the size of metastases, had a correspondingly high odds ratio. Conclusions: We identified 8 factors predictive of NSN metastases that should be recorded and evaluated routinely in SLN databases. These factors should be included in a predictive model that is generally applicable among different populations. (C) 2011 Elsevier Ltd. All rights reserved.