Sentinel lymph node identification in breast cancer: a comparison study of deep versus superficial injection of radiopharmaceutical

OBJECTIVESSentinel lymph node biopsy (SLNB) has been performed for purposes of disease staging. SLN is usually located in the axillary region and internal mammary chain (IMC). Metastasis in internal mammary nodes can be an important prognostic factor and an indication for systemic treatment in patients with small carcinomas. The SLNB technique continues to evolve and the proper radiopharmaceutical injection route remains under discussion. This study evaluated the success rate of deep injection to identify axillary and extra-axillary SLNs and compared the results with superficial injection technique. METHODSForty-six patients diagnosed with breast cancer (stages I and II) were submitted to radiopharmaceutical injection. Deep injection of technetium-99m-dextran 500 was carried out in 20 patients (group A) and periareolar injection of technetium-99m-phytate was carried out in 26 patients (group B). All SLNs were studied by imprint cytology and hematoxylin and eosin staining. RESULTSSLN identification rate was 76.1% (35 of 46). The SLN identification rate was 75% (15 of 20) for group A and 76.9% (20 of 26) for group B. Axillary SLNs were identified in 65% (13 of 20) of group A and 76.9% (20 of 26) of group B, with no statistical difference (P = 0.75). Extra-axillary SLNs were only identified in group A, and IMC was the principal extra-axillary location. CONCLUSIONDeep injection of radiopharmaceutical achieved a good SLN identification rate in axillary and extra-axillary locations and it is an important method for detecting IMC sentinel nodes.