Validity of sentinel lymph node biopsy in breast cancer patients after neoadjuvant chemotherapy

Abstract

11023 Background: Sentinel lymph node biopsy (SLNB) is a potential alternative procedure to conventional axillary lymph node dissection (ALND) in clinically node-negative breast cancer patients. Neoadjuvant chemotherapy (NAC) is a standard of care for patients with locally advanced breast cancer and indications of NAC have been widespread to operable breast cancer patients to facilitate breast conserving surgery. However, the validity of SLNB in breast cancer patients who received NAC is still controversial. Methods: Forty-six patients with stage II or III breast cancer who were treated with NAC from January 2002 to May 2006 were included in the study. Consecutive 122 patients who had SLNB without NAC during the same period were used as a control group. All patients underwent SLNB followed by completion ALND. Sentinel lymph node (SLN) was detected using a combined method of injecting isosulfan blue dye and small-sized technetium- 99m-labeled tin colloid (particle size: 200–400 nm in diameter) peritumorally and subcutaneously. SLNs were evaluated by means of H&E and immunohistochemical staining. Results: SLNs were successfully identified in 42/46 patients (91.3%) treated with NAC and 112/113 patients (99.1%) without NAC (p=0.01). Metastases in the SLNs were found in 16/42 patients (38.1%) with NAC and 32/112 patients (28.6%) without NAC (p=0.2). There were 5 false negative cases (false negative rate: 23.8%) in the NAC group and 2 false negative cases (false negative rate: 5.9%) in the control group (p=0.05). Accuracy of SLNB in the NAC group was also significantly inferior to the control group (88.1% vs. 98.2%, p<0.01). The presence of clinically positive axillary lymph nodes before NAC was not correlated with false negative rate. Conclusions: These data suggest that NAC might be considered a contraindication to SLNB even in patients with clinically negative axillary lymph nodes before NAC. No significant financial relationships to disclose.