There is a validation study of lower axillary sampling versus total axillary clearance reported by Steele et al in 1985 with a sensitivity of 100% and an accuracy of 99.5%. The more recent validation study of 5-node axillary sampling compared to level I-II dissection was reported from Stockholm on 416 operable breast cancer patients. The noteworthy finding was that in this study node sampling had a 100% yield, 97.3% sensitivity and a negative predictive value of 98.5% with a false negative rate of 2.7% in predicting the axilla. The comparative figures for SNB in the world overview are 94% sensitivity, 97% negative predictive value and a false negative rate of 6.5%.