Background: Radiotracer and blue dye mapping of sentinel lymph nodes (SLN) have been advocated as accurate methods to stage the clinically negative axilla in breast cancer patients. The technical aspects of SLN biopsy are not fully characterized. In this study we compare the results of intraparenchymal (IP) and intradermal (ID) injection of Tc-99m sulfur colloid, to establish an optimal method for SLN localization.
Methods: 200 consecutive patients had SLN biopsy performed by a single surgeon. Of these, 100 (Group I) had IP injection and 100 (Group II) had ID injection of Tc-99m sulfur colloid. All patients had IP injection of blue dye as well. Endpoints included (1) successful SLN localization by lymphoscintigraphy, (2) successful SLN localization at surgery, and (3) blue dye-isotope concordance (uptake of dye and isotope by the same SLN).
Results: Isotope SLN localization was successful in 78% of Group I and 97% of group II patients (P < .001). When isotope was combined with blue dye, SLN were found in 92% of group I and 100% of Group II (P < .01). In cases where both dye and isotope were found in the axilla, dye mapped the same SLN as radiotracer in 97% of Group I and 95% of Group II patients.
Conclusions: The dermal and parenchymal lymphatics of the breast drain to the same SLN in most patients. Because ID injection is easier to perform and more effective, this technique may simplify and optimize SLN localization.