Pathologic features associated with nonsentinel lymph node metastases in patients with metastatic breast carcinoma in a sentinel lymph node

BACKGROUND: To the authors' knowledge it has not yet been determined which patients with primary breast carcinoma and an axillary sentinel lymph node (SN) metastasis have additional metastases in nonsentinel lymph nodes. METHODS: Pathologic features of the primary breast carcinoma and its SN metastasis were examined in 194 patients and correlated with the tumor status of the non-SNs in the same axillary basin. Two-level cytokeratin immunohistochemistry was applied to the SNs and to non-SNs of cases that were negative by standard hematoxylin and eosin examination. RESULTS: Lymph node staging based on SN findings, size of the primary tumor, and presence of peritumoral lymphatic vascular invasion (LVI) were associated with non-SN metastasis. The majority (63%) of the 101 patients with SN macrometastases had non-SN metastases. Extranodal hilar tissue invasion in conjunction with SN involvement also was strongly associated with non-SN metastasis (P = 0.0001) but was present in only 65% of patients (35 of 54 patients) with non-SN macrometastases. Approximately 26% of patients (24 of 93 patients) with SN micrometastases (