Tumor characteristics predictive of sentinel node metastases in 105 consecutive patients with invasive lobular carcinoma

Background: Identification of nodal metastases in invasive lobular carcinoma (ILC) is difficult. Sentinel node (SN) biopsy offers a potential advantage. This study reports the feasibility of SN identification and predictors of SN metastases for ILC. Methods: All cases of ILC undergoing sentinel lymphadenectomy between October 1991 and May 2001 were evaluated. Patients enrolled in ACOSOG Z0010/Z0011 were excluded. Presentation, surgical treatment, tumor characteristics, and prognostic factors were analyzed for statistical significance. Results: SN mapping was performed in 105 patients with 106 cases of ILC. SN identification was 97%, accuracy 100%, and positivity 50% with 45% macrometastases, 16% micrometastases, and 39% immunometastases. There are no axillary recurrences at 43.73 months. Palpable tumor, increasing tumor size, and angiolymphatic invasion are statistically significant for SN-positive status. Conclusions: SN staging for ILC is feasible and accurate. Receptor status and proliferative indices are not useful markers for metastases. However, large tumor size and presence of angiolymphatic invasion are positive predictors. (C) 2002 Excerpta Medica, Inc. All rights reserved.