Clinical relevance of nonvisualized sentinel lymph nodes in unselected breast cancer patients during lymphoscintigraphy

Background: Sentinel lymph node (SLN) biopsy in breast cancer is an effective technique with a high degree of accuracy and low false-negative rate to replace axillary lymph node dissection (ALND). This study analyzed the major clinicopathological factors associated with nonvisualized sentinel nodes during preoperative lymphoscintigraphy. Methods: Breast cancer patients who underwent preoperative lymphoscintigraphy and sentinel node biopsy between 2000 and 2003 were retrospectively reviewed. Sentinel node biopsy was performed with a two-day protocol. On day one, a filtered (45 μ m Millipore) technetium-99m sulfur colloid isotope with a mean radioactive dose of 37 MBq (1 mCi) in a diluted volume of 1 ml was injected subdermally just above the primary breast tumor site. Serial dynamic images were taken with a high-resolution collimator and a static image was acquired after the SLN was identified. No hot spot identified two hours after injection was classified as nonvisualization unless lymphatic drainage channels were viewed by the lymphoscintigraphy and a prolonged two hour scan was obtained. Sentinel nodes were harvested on day two. The cases with nonvisualized sentinel nodes were analyzed according to clinical histopathologic parameters to determine the clinical significance. Results: A total of two hundred thirty-two breast cancer patients were enrolled in this study. Twenty-four of these cases presented with advanced breast cancer prior to neoadjuvant chemotherapy. The sentinel node was nonvisualized in twenty-seven of two hundred thirty-two cases (11.6%). Tumor size (p = 0.025) and lymph node metastasis (p = 0.001) were two factors associated with nonvisualized sentinel node in univariate analysis. Multivariate logistic regression analysis showed that more than three nodes (p = 0.001) and more than ten nodes (p = 0.001) metastasis were independent factors associated with nonvisualized sentinel node. Conclusions: Patients with more than three axillary nodes metastasis is an independent factor associated with nonvisualized sentinel node during lymphoscintigraphy.