Identification of the sentinel lymph node in the SNAC-1 trial.

Abstract

A combination of scintigraphy and a lymphotropic dye (patent blue dye (BD)) is the recommended technique to detect the sentinel lymph node (SLN) in early breast cancer. This study determined the effect of clinical factors on SLN identification in the sentinel node biopsy versus axillary clearance (SNAC) trial. A total of 1088 women were registered. Lymphatic mapping was performed using preoperative lymphoscintigraphy (LSG) and gamma probe (GP) combined with peritumoural injection of patent BD (971 patients) or BD alone (106 patients). SLNs were identified in 1024 women (94%), localized with LSG in 779 (81.4%), and were identified by GP in 879 (91.8%). The BD identified SLNs in 890 of 1073 (82%) women. Three patients had allergic reactions. BD detected the SLNs in 141 of 178 women with negative LSG mapping and in 44 of 79 women with no hot SLNs detected intraoperatively. Age, body mass index (BMI) and tumour presentation (screen detected versus symptomatic) were significantly related to the identification of the SLN. For BD, the primary tumour location was significantly related to identification rate. The detection of blue SLN was significantly lower in women with inner quadrant tumours. The combined technique resulted in a high identification rate. BD contributed to the identification of the SLNs in patients where LSG and GP failed to identify the sentinel node. Special attention to these techniques is needed in particular groups of patients such as those with high BMI, screen-detected primary tumours and tumour located in the inner quadrants.