Comparison between periareolar and peritumoral injection of radiotracer for sentinel lymph node biopsy in patients with breast cancer

Background. The technique of sentinel lymph node (SLN) biopsy in patients with breast cancer varies among reports, and the optimal method remains to be established, particularly with regard to the site of radiotracer injection. The aim of this study was to compare periareolar and peritumoral injection of radiotracer in detecting SLN in patients with breast cancer. Methods. Patients with T1-2 breast cancer (n = 155) were enrolled in this study. In phase 1 (n = 62), SLN biopsy was performed by using peritumoral injection of blue dye alone followed by backup axillary lymph node dissection. In phase 2, SLN biopsy was performed by using peritumoral injection of blue dye and peritumoral (group A, n = 41) or periareolar (group B, n = 52) injection of technetium 99m, tin colloid. Results. In phase 1, the detection rate of SLN was 81% and the false-negative rate was 5.6%, indicating our skill in SLN biopsy. In phase 2, the success rate of lymphoscintigraphy was significantly (P < .001) higher in group B (90%) than in group A (51%) The mean ex vivo radioactivity, of SLN in group B (117 counts per second; range, 5 to 900) was also significantly (P < .05) higher than in group A (51 counts per second; range, 8 to 260). In addition, the detection rate of SLN was significantly (P < .05) higher in group B (100%) than in group A (90%). Conclusions. Periareolar injection of radiotracer for SLN biopsy is superior to peritumoral injection because of its simplicity, achieving a high success rate in lymphoscintigraphy and SLN detection.