Comparison of blue dye and gamma probe guided sentinel lymph node biopsy techniques in breast cancer patients

The introduction of sentinel lymph node (SLN) biopsy has brought an innovative approach to the staging of early breast cancer. Up to date two methods have been described: a blue dye-guided lymphatic mapping procedure and a radioactivity guided SLN biopsy technique using a handheld gamma probe. Aim of this study was to test the sentinel lymph node concept which states the histopathological analysis of sentinel lymph node is highly predictive of metastatic involvement of other lymph nodes and to compare gamma probe and blue dye techniques in the detection of sentinel lymph node in breast cancer. Twenty-eight patients with unifocal primary invasive breast cancer and clinically negative axilla scheduled for mastectomy/lumpectomy and ALND were included into the study. Gamma probe successfully identified SLN in 71% (20/28) of patients. Blue Dye identified SLN in 61% (17/28) of patients. Either Blue dye or gamma probe identified SLN in 79% (22/28) of patients. The mean number of SLNs that were identified was 1.36. Gamma probe identified more SLNs compared to blue dye and results of statistical analysis show a significant difference between them (Fisher’s exact chi-square test, p=0.03). Analysis of data revealed that learning curve has a significant effect on the success of SLN identification. The success rate in first 6 patients was 33% (2/6) while it was 91% (20/22) in the last 22 patients. Histopathological analysis of SLN accurately predicted absence of the disease in the axilla in 15 patients. In four patients there were metastatic involvement in both SLN and other axillary lymph nodes. In two patients micrometastasis was detected in SLN by immunohistochemistry while non-SLNs were negative. There was one false negative SLN biopsy, where histopathological investigation of SLN was negative for metastases while nonSLN were positive. We concluded that there is statistically significant difference between blue dye and gamma probe techniques for identifying SLN and gamma probe identifies more SLN compared to blue dye. However, they are complementary techniques and combined method works better. This study also supports the clinical validity of SLN biopsy in breast cancer and confirms that histopathological analysis of sentinel lymph node is highly predictive of metastatic involvement of other non-SLNs in axilla. [Turk J Cancer 2003;33(2):82-90]