Preoperative dynamic lymphoscintigraphy predicts sentinel lymph node metastasis in patients with early breast cancer

Preoperative lymphoscintigraphy is commonly used in sentinel lymph node biopsy (SLNB) for patients with early breast cancer; however, its significance to predict SLN metastasis remains to be determined.

Sixty patients were enrolled in a feasibility study of SLNB. Patients with clinically node-negative breast cancer were eligible for this study. Dynamic lymphoscintigraphy was performed before SLNB. All patients underwent SLNB followed by axillary lymph node dissection.

A dual mapping procedure using isotope and dye injections was performed. SLNs were identified in 59 of 60 patients (98.3%), with a node-positive rate of 41.7% and a false-negative rate of 1.7%. No SLN was identified in 4 of 60 patients (6.7%) on preoperative lymphoscintigraphy. Interestingly, abnormal accumulation of the radiotracer close to hot spots was observed in 29 of 56 patients (51.8%). Lymph node metastases were detected in 18 of 29 patients (62.0%) with this pattern and 5 of 27 patients (18.5%) without this pattern (P < 0.05). Micrometastases were more frequently detected in node-positive patients without this pattern than in those with this pattern (80 vs. 16.7%). Diagnostic parameters of this pattern to predict SLN metastases, including micrometastases, were 62.1% for sensitivity, 81.5% for specificity, and 71.4% for accuracy.

Abnormal accumulation of the radiotracer close to radioactive spots may indicate SLN metastasis. When dynamic lymphoscintigraphy shows this pattern, surgeons should consider the presence of SLN metastasis and carefully remove additional lymph nodes surrounding radioactive lymph nodes so as not to leave metastatic SLNs behind.