Архив хирургической онкологии

Significance of Sentinel Lymph Nodes with Low Gamma Counts in Breast Cancer Patients via Radioisotopic Sentinel Lymph Node Biopsy

Abstract

Kazuma Maeno, Tokiko Ito, Hiroshi Koyama, Toshiharu Kanai, Yasuhiro Mochizuki and Ken-ich Ito

Objective: Sentinel lymph node biopsy (SLNB), a standard diagnostic procedure worldwide, uses blue dye and/or radioisotopic methods to detect clinically node-negative breast cancer. With the latter method, we often experience axillary lymph nodes with extremely low levels of radioactivity, compared with the maximum radioactive nodes. Here, we investigated the significance and possibility of metastasis in low radioactive SLNs in patients with and without metastasis in maximum radioactive SLNs.
Patients and methods: Between 2003 and 2011, we subjected a total of 453 breasts in 443 patients with earlystage invasive ductal carcinoma to SLNB using a combination of blue dye and radioisotopic methods. All lymph nodes detected via gamma -probe were considered SLNs and resected.
Results: SLNs were identified in 452 (99.8%) of 453 cases; of these, SLN metastasis was pathologically diagnosed in 118 cases (26.1%). Two or more SLNs were detected in 232 (51.2%) of 453 cases; of these, 46 cases (19.8%) had SLNs with gamma counts < 10% of the maximum detected values. Metastasis was detected in these low-gamma-count SLNs in 4 of 453 cases (0.9%), even though no metastasis had been detected in SLNs with maximum radioactivity levels. Macrometastasis was pathologically demonstrated in 3 of 4 cases. Conclusion: We identified several cases of metastatic SLNs with very low radioactivity, despite a lack of metastasis in SLNs with maximum radioactivity. These findings indicate that the evaluation of SLNs with gamma counts < 10% of the patient maximum would provide more precise information about the axillary status and help to maintain a low SLNB false-negative rate.