Abstract P1-01-10: Sentinel lymph node-II biopsy in breast cancer: A novel method to accurately predict non-sentinel axillary lymph node status

Abstract

Abstract Background: In breast cancer patients, axillary lymph node dissection (ALND) is recommended in the presence of sentinel lymph node metastasis (SLNM). However, in 50-70% of patients, SLN is the only site affected by metastasis and thus majority of these patients are exposed to risk of morbidity of ALND without any benefit. Z011 trial suggests avoiding ALND in early breast cancer patients with isolated SLNM. However, this trial results are not applicable to women with advanced T-stage, multiple SLNM, and the presence of lympho-vascular or peri-capsular invasion. This prospective study aims to analyze whether SLN-II biopsy would help in accurate prediction of non sentinel axillary metastases in the presence of metastatic SLN-I. Methods: After IRB approval, 65 patients with biopsy proven breast cancer underwent SLN biopsy using a standard technique. After identification of the SLN-I, 0.1 cc of methylene blue dye was injected into SLN-I, and the lymphatic channels were traced to identify SLN-II station. ALND was performed in the presence of SLNM. After a pathologic examination, the sensitivity and specificity of SLN-II and the concordance rate between SLN-I, SLN-II and the axilla were calculated to determine the accuracy of SLN-II in identifying the non-sentinel axillary metastasis. Results: A total of 65 breast cancer patients underwent SLN-I and SLN-II biopsy. Average number of SLN-I harvested was 1.7 (range 1-5) and that of SLN-II was 1.4 (range 1-4). Metastases to SLN-I were identified in 12 (18.5%) patients. Upon ALND, only 3 (25%) patients had higher axillary metastasis whereas in 9 patients (75%), axilla had no metastasis. SLN-II predicted the presence (3 of 3) or absence (9 of 9) of axillary metastases with 100% accuracy. The sensitivity, accuracy, false negative rate and negative predictive value of SLN-I in identifying higher axillary metastasis were 92.3%, 98.5%, 7.7% and 98% respectively, whereas same metrics for SLN-II were 100%, 100%, 0% and 100% respectively. Utility of different sentinel lymph node stations in determining axillary metastasesTestTrue positiveTrue negativeFalse negativeSLN-I12521SLN-II4610ALND390 Thus in the presence of SLN-I metastasis, SLN-II accurately identified axillary involvement 100% of the times. One patient was associated with a skip SLN-II metastasis. In this patient SLN-I was negative, however non-sentinel metastases were noted upon ALND. Comparitive analysis of SLN-I and SLN-II in determining axillary metastasisTestSensitivityFNRNPVAccuracyNLRSLN-I12/13 (92.3%)1/13 (7.7%)52/53 (98%)64/65 (98.5%)77%SLN-II4/4 (100%)0%61/61 (100%)65/65 (100%)100%NLR: negative likelihood ratio, NPV, negative predictive value Conclusions: This study demonstrates that in breast cancer patients with SLN-I metastases, SLN-II biopsy is feasible and accurately predicts the higher axillary lymph node status in terms of either the presence or absence of metastasis. In other words, in patients with SLN-I metastasis, a negative SLN-II rules out higher axillary metastasis, whereas the presence of the SLN-II metastasis was associated with further axillary metastasis. Thus, ALND can be avoided in women with isolated SLN-I metastasis but absent SLN-II involvement. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-01-10.