Multicentre validation study of sentinel node biopsy for staging in breast cancer

Background: The aim of this study was to validate sentinel node biopsy for axillary staging after the initial learning phase, and to analyse factors associated with false-negative biopsies. Methods: Some 675 patients, who had standard sentinel node biopsy followed by level I and II axillary clearance in one of 20 hospitals in Sweden and were operated on by 36 different surgeons, were recruited prospectively. Results: The overall detection rate was 94.5 per cent. It varied between surgeons but was not influenced by the number of operations per surgeon. Moreover, it was lower among older patients. The overall false-negative rate was 7.7 per cent. This rate was not affected by patient age, tumour histological type or Elston grade, but was increased in patients with multifocal tumours. Some 21 per cent of patients with a multifocal tumour diagnosed on postoperative histopathological analysis had a false-negative biopsy compared with 5.6 per cent of those with unifocal tumours (P = 0.004). Conclusion: Sentinel node biopsy was shown to be a reliable method for axillary staging of unifocal breast tumours.