The aim of this study was to define the factors associated with nonvisualization of a sentinel node (SN) in the axilla area during preoperative lymphoscintigraphy.
Methods: We retrospectively studied 332 women with T0, T1, or T2 <3-cm, N0 invasive breast cancer who underwent a sentinel lymph node biopsy procedure. All patients had intradermal and intraparenchymal injection of 37 MBq (99m)Tc-sulfur colloid in a total volume of 4 x 0.1 mL, above and around the tumor. Anterior and lateral static views were obtained a few minutes and 2-4 h after injection. Surgery was performed the next day. The SNs were localized intraoperatively with the aid of patent blue dye and using a hand-held gamma-probe. SNs were analyzed by serial sections stained with hematoxylin-eosin, with the adjacent section stained with anticytokeratin antibodies. Different parameters, such as the number of positive lymph nodes, presence of lymphovascular invasion, tumor size, tumor grade, histology (invasive vs. in situ), prior excisional biopsy, and patient age were analyzed to determine whether they had any significant correlation with nonvisualization of SNs in the axillary area.
Results: An axillary SN was successfully visualized on the preoperative lymphoscintigraphy in 302 of 332 patients (90.7%). No axillary drainage was found in 30 patients on the delayed images, even after a second injection of radiocolloid, and 5 of 30 patients showed uptake outside the axillary area. Positive nodes were identified in 86 of 302 patients (28.5%) with successful axillary drainage and in 19 of 30 patients (63.3%) with unsuccessful axillary drainage. More than 4 invaded axillary nodes (P < 0.0001) and the presence of lymphovascular invasion in the breast tumor (P = 0.004) were the only significant variables on univariate analysis, although multivariate analysis showed that only the increased number of invaded nodes was statistically significant.
Conclusion: Patients with unsuccessful axillary mapping have an increased risk for axillary involvement.