INTRODUCTION: Axillary lymphadenectomy is the gold standard for sentinel node metastasis (SN). Metastasis rate of non – sentinel node (NSN) is related to tumor and SN metastasis sizes. In over 50% of cases of SN metastasis, the SN is the only node with neoplasm involvement. We have studied the variables that are known to influence most on SN metastasis (tumor size) and on NSN metastasis (size of the SN metastasis) with the aim to find out a subgroup of patients in whom axillary lymphadenectomy could be avoided despite of SN involvement.OBJECTIVE: To determine if lymphadenectomy is necessary in all patients with SN metastasis.MATERIAL AND METHOD: A sequential and prospectively maintained database was retrospectively searched, for patients staged with SN biopsy for breast carcinoma. We have reviewed 1285 consecutive breast cancer patients treated between December 1998 and April 2009, average age: 55 ± 12.5 years. SN localization was performed with isotopic (34%) or combined technique (66%). SN biopsy was associated to breast conserving technique in 79.8% of cases. The histopathologic study of SN consisted of serial sectioning, H&E and immunohistochemical (IHC) staining.Statistical analyses were performed using SPSS version 15.0 (SPSS Inc, Chicago, Ill). Comparisons of NSN tumoral infiltration among groups (negative SN, isolated tumoral cells (ITC) and SN micrometastasis) related to tumoral size were assessed by univariate analysis with contingency tables and χ2 test. Multivariate analysis was performed using a binary logistic regression model.RESULTS: Identification rate was of 95.8%. SN metastasis was detected in 418 patients, axillary lymphadenectomy was the treatment in 384 cases. The SN was the only metastatic lymph node in 276 patients (71.9%), whereas more involved nodes were found in 108 patients (28.1%). On multivariate analysis, the variables independently associated to SN metastasis were: age (p=0.005), tumor size (p<0.005) and lymphovascular infiltration (LVI) (p=0,005) and the size of the SN metastasis was an independent factor (p=0.005) related to NSN metastasis.In all the 150 cases where the tumor size was ≤ 10 mm, there was no significant difference in NSN involvement between the three forms of SN (negative, micrometastasis, ITC) (p=0,132).CONCLUSIONS: SN metastasis was associated to younger age, large tumor size and LVI. NSN metastasis, in case of SN involvement, is related to the extent of the SN metastasis. In tumors ≤ 10mm where a micrometastasis is found in the SN, axillary lymphadenectomy could be omitted, due to the insignificant difference related to NSN involvement.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1027.