Subareolar versus peritumoral injection for location of the sentinel lymphnode

Background Sentinel lymph node (SLN) biopsy is fast becoming the standard f or testing lymph node involvement in many institutions. However, questions remain as to the best method of injection. The authors hypothesized that a subareolar injection of material would drain to the same lymph node as a pe ritumoral injection, regardless of the location of the tumor. Methods To test this theory, 68 patients with 69 operable invasive breast c arcinomas and clinically node-negative disease were enrolled in this single -institution Institutional Review Board-approved trial. Patients were injec ted with 1.0 mCi of technetium-99 sulfur colloid (unfiltered) in the subare olar area of the tumor-bearing breast. Each patient received an injection o f 2 to 5 cc of isosulfan blue around the tumor. Radioactive SLNs were ident ified using a hand-held gamma detector probe. Results The average age of patients entered into this trial was 55.2 +/- 13 .4 years. The average size of the tumors was 1.48 +/- 1.0 cm. Thirty-two pe rcent of the patients had undergone previous excisional breast biopsies. Of the 69 lesions, 62 (89.9%) had SLNs located with the blue dye and 65 (94.2 %) with the technetium. In four patients, the SLN was not located with eith er method. All blue SLNs were also radioactive. All located SLNs were in th e axilla, Of the 62 patients in which the SLNs were located with both metho ds, an average of 1.5 +/- 0.7 SLNs were found per patient, of which 23.2% h ad metastatic disease. Aii four patients in which no SLN was located with e ither method had undergone prior excisional biopsies. Conclusions The results of this study suggest that subareolar injection of technetium is as accurate as peritumoral injection of blue dye. Central inj ection is easy and avoids the necessity for image-guided injection of nonpa lpable breast lesions. Finally, subareolar injection of technetium avoids t he problem of overlap of the radioactive zone of diffusion of the injection site with the radioactive sentinel lymph node, particularly in medial and upper outer quadrant lesions.