Prediction in breast cancer of the extent of axillary node involvement from the size and lymphovascular invasion status of the primary tumour: Medico-legal considerations

Aim To ascertain for medico-legal purposes in the United Kingdom, the extent to which in breast cancer primary tumour size and lympho-vascular invasion (LVI) status determine axillary node staging. Methods Four hundred and fifty symptomatic patients had their tumour sizes stratified into 1 cm ranges and the percentage incidence/probability of the axillary stage being 1, 2 or 3 was calculated separately for those tumours that showed no evidence of LVI and those that did. Results The presence of LVI has a marked effect on the likelihood and extent of axillary node involvement for all primary tumour sizes. Conclusions This needs to be recognized and quantified when prediction of this extent is made for medico-legal purposes. Within the constraints of the ‘balance of probabilities’ argument in UK law, it is rarely possible to differentiate between the likelihood of the axillary stage being 2 or 3.