Result of sentinel lymph node biopsy using radioisotope in clinically lymph node negative breast cancer

Purpose: Sentinel lymph node biopsy (SLNB) has been developed to accurately assess the axillary lymph node status accurately without having to remove most of the axillary contents in node negative early breast cancer patients. The aims of this study were to evaluate the accuracy, the false negative rate and the advantage of additional axillary sampling for SLNB with using radioisotope. Methods: Between December 2003 and June 2005, we carried out SLNB for 574 breast cancer patients who were diagnosed and had operation at Asan Medical Center. For detection of the sentinel lymph mode (SLN), radioisotope was injected into the periareolar area on the operating day, breast scintigraphy was performed and finally the biopsy was done using a gamma-detection probe in the operating room. If the SLN turned out to be positive for metastatic malignancy according to the frozen section histology, then additional axillary lymph nodes (LN) dissection was performed. But, if it was free of metastasis, then only axillary node sampling (n <= 5) or no further treatment was done. Results: The mean number of resected SLNs was 2.67 +/- 0.98 (1-7) and the mean number of total LN was 8.5 +/- 5.0 (1-38). The SLN was detected 82.8% of the time on lymphoscintigraphy and 98.4% of the time with the gamma probe. Axillary metastasis was founded in 118 cases (20.9%). The accuracy was 98.2%, and the false negative rate was 7.89%. For the SLN positive cases, there were 73/78 cases (93.6%) of list SLN metastasis, there were 75/78 cases (93.6%) of 1st and 2nd SLN metastasis, and 75178 (93.6%) of 1 st to 3rd SLN metastasis. The false negative rate of the alternative frozen section was 40% and that of the full frozen section was 24.1%. The difference was statistically significant. Conclusion: SLNB using Tc-99m-antimony trisulfide colloid (0.5 mCi) showed a high detection rate and a low false negative rate. The false negative rate was decreased by using full section H&E staining and at least 3 SLNs showed the exact LN status. Even if the SLN was free of metastasis, additional sampling may decrease the false negative rate.