Low Sentinel Node Biopsy False-Negative Rate With Immunohistochemistry After Neoadjuvant Chemotherapy in Biopsy-Proven Node-Positive Breast Cancer
In the phase II SN FNAC (Sentinel Node Biopsy Following Neoadjuvant Chemotherapy) trial, reported in the Journal of Clinical Oncology, Boileau et al found a sentinel node biopsy false-negative rate of 8.4% with mandatory use of immunohistochemistry and a sentinel node biopsy identification rate of 87.6% after neoadjuvant therapy in patients with biopsy-proven node-positive breast cancer.
Study Details
In the study, 145 eligible patients with biopsy-proven stage II to IIIA (T0-T3, N1-2, M0-X) breast cancer were accrued between March 2009 and December 2012 from 10 university-affiliated centers in Canada and the United States. All patients underwent sentinel node biopsy and complete nodal dissection. Immunohistochemistry use was mandatory, and sentinel node metastases of any size, including isolated tumor cells (ypN0[i+], ≤ 0.2 mm), were considered positive. Predetermined optimal rates were ≥ 90% for sentinel node biopsy identification and ≤ 10% for false-negatives.
Identification and False-Negative Rates
The sentinel node biopsy identification rate was 87.6% (127/145; 95% confidence interval [CI] = 82.2%–93.0%), and the false-negative rate was 8.4% (7/83; 95% CI = 2.4%–14.4%). The negative predictive value of sentinel node biopsy was 86.3% (44/51). In cases of technical failure, the rate of positive nodal involvement was 66.7% (12 of 18). The axillary pathologic complete response rate was 34.5% (50 of 145). It was estimated that 30.3% (44/145) of patients in the study could have potentially avoided node dissection if sentinel node biopsy alone had been used after neoadjuvant therapy.
The false-negative rate increased to 13.3% (11/83; 95% CI = 6.0%–20.6%) when ypN0(i+) metastases were considered as negative findings. False-negative rate and accuracy were 18.2% and 87.5% when only one sentinel node was obtained and 4.9% and 96.8% when at least two were obtained (P = .076 for false-negative rate). There was no correlation between size of metastases and rate of positive nonsentinel nodes.
The investigators concluded: “In biopsy-proven node-positive breast cancer after [neoadjuvant chemotherapy], a low [sentinel node biopsy false-negative rate] (8.4%) can be achieved with mandatory use of [immunohistochemistry]. [Sentinel node] metastases of any size should be considered positive. The [sentinel node biopsy identification rate] was 87.6%, and in the presence of a technical failure, axillary node dissection should be performed. We recommend that [sentinel node] evaluation with [immunohistochemistry] be further evaluated before being included in future guidelines on the use of [sentinel node biopsy] after [neoadjuvant chemotherapy] in this setting.”
Jean-Francois Boileau, MD, of Jewish General Hospital Segal Cancer Centre, Montreal, is the corresponding author for the Journal of Clinical Oncology article.
The study was supported by the Quebec Breast Cancer Foundation, Cancer Research Society, Week-end to End Women’s Cancers, and Montreal Jewish General Segal Cancer Centre. The study authors reported no potential conflicts of interest.
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