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Sentinel node biopsy after neoadjuvant chemotherapy in biopsy-proven node-positive breast cancer: the SN FNAC study
Jean-Francois Boileau1, Brigitte Poirier2, Mark Basik2
1Jean-Francois Boileau, Mark Basik, and Andre Lisbona, Montreal Jewish General Segal Cancer Centre, McGill University; Louis Gaboury, Isabelle Trop, Rami J. Younan, Erica Patocskai, and Andre Robidoux, Centre Hospitalier de l'Universite de Montreal; Lucas Sideris, Hopital Maisonneuve Rosemont, Universite de Montreal; Sarkis Meterissian and Atilla Omeroglu, McGill University Health Centre, Montreal; Brigitte Poirier and Louise Provencher, Hopital Saint-Sacrement, Universite Laval, Quebec City, Quebec; Claire M.B. Holloway and Frances C. Wright, Sunnybrook Odette Cancer Centre, University of Toronto; David R. McCready, University Health Network, University of Toronto, Toronto; Angel Arnaout, Ottawa Hospital, University of Ottawa, Ottawa; Muriel Brackstone, London Regional Cancer Program, University of Western Ontario, London, Ontario, Canada; and Stephen E. Karp, Lahey Hospital and Medical Center, Tufts University School of Medicine, Boston, MA. jean-francois.boileau@mcgill.ca.
Purpose:
An increasing proportion of patients (> 30%) with node-positive breast cancer will obtain an axillary pathologic complete response after neoadjuvant chemotherapy (NAC). If sentinel node (SN) biopsy (SNB) is accurate in this setting, completion node dissection (CND) morbidity could be avoided.
Patients And Methods:
In the prospective multicentric SN FNAC study, patients with biopsy-proven node-positive breast cancer (T0-3, N1-2) underwent both SNB and CND. Immunohistochemistry (IHC) use was mandatory, and SN metastases of any size, including isolated tumor cells (ypN0[i+], ≤ 0.2 mm), were considered positive. The optimal SNB identification rate (IR) ≥ 90% and false-negative rate (FNR) ≤ 10% were predetermined.
Results:
From March 2009 to December 2012, 153 patients were accrued to the study. The SNB IR was 87.6% (127 of 145; 95% CI, 82.2% to 93.0%), and the FNR was 8.4% (seven of 83; 95% CI, 2.4% to 14.4%). If SN ypN0(i+)s had been considered negative, the FNR would have increased to 13.3% (11 of 83; 95% CI, 6.0% to 20.6%). There was no correlation between size of SN metastases and rate of positive non-SNs. Using this method, 30.3% of patients could potentially avoid CND.
Conclusion:
In biopsy-proven node-positive breast cancer after NAC, a low SNB FNR (8.4%) can be achieved with mandatory use of IHC. SN metastases of any size should be considered positive. The SNB IR was 87.6%, and in the presence of a technical failure, axillary node dissection should be performed. We recommend that SN evaluation with IHC be further evaluated before being included in future guidelines on the use of SNB after NAC in this setting.
