Prediction of Nonsentinel Lymph Node (NSLN) Metastasis in Breast Cancer Patients; The Usefulness of Isotope Counts for Sentinel Lymph Node (SLN) Classification

Lee, Dong Hee; Kim, Bum Seok; Kang, Su Hwan; Lee, Nam Hyuk; Lee, Soo Jung; Bae, Young Kyung

Abstract

PURPOSE: The goal of this study was to identify a patient subgroup with a positive SLN where exposure to the morbidity and cost associated of an axillary lymph node dissection (ALND) is not required. To achieve this goal, we subdivided SLNs according to their isotope counts, and then assessed whether the number of positive SLNs and subdivided status were related to the axillary NSLN status.
METHODS
During SLN biopsies, the ex vivo isotope counts were measured for each SLN. Each SLN was labeled as S1, S2 or S3, and so on, in descending count order. An SLN biopsy was performed until the isotope counts of the axilla equaled that of the background. If SLNs were positive, a completion ALND (cALND) was performed. The pathological report was also reviewed and analyzed.
RESULTS
SLNs were successfully identified in 243 (99.6%) of 244 patients, with metastases in SLNs identified in 28.0% of patients. An SLN was the only positive lymph node in 52.9% (36/68) of patients, with a positive SLN followed by a cALND. NSLNs metastases were found in 32/68 cases (47.1%). The rate of NSLN metastasis was positively correlated with the number of positive SLN (P=0.017). In SLN positive patients, the NSLN metastasis rate was 60.9% (28/46) in patient with a tumor-harboring last-order SLN (SLN with least isotope counts), but only 18.2% (4/22) in patients with a tumor-free SLN (P=0.001). Similar results were found in patients with either two or more metastatic SLNs (P=0.023).
CONCLUSION
In patients with a positive SLN, the number of metastatic SLNs and their isotope counts can be useful in the prediction of NSLNs metastasis. Further investigation will be necessary to confirm these results.