Background: Although sentinel lymph node biopsy (SLNB) has become the standard for patients with clinically lymph node-negative breast cancer, less than one third of patients who undergo SLNB will have lymph node metastases. Therefore, we hypothesized that a subset of patients in whom SLNB can be avoided can be identified before operation. Methods: We prospectively studied 220 patients with early stage breast cancer who underwent SLNB. We analyzed primary tumor features, biologic markers, and demographic data. Results: Overall, 31% of the patients had lymph node metastases. Although patients with lymph node metastases had larger neoplasms than patients who were lymph node negative (mean, 2.3 ± 0.1 cm versus 1.5 ± 0.1 cm; P < .0001), 10% of patients with T1a tumors, 19% of patients with T1b tumors, and 30% of patients with T1c tumors had lymph node metastases. Palpable tumors were lymph node positive in 41% of patients versus 17% for nonpalpable tumors (P = .0001). Lymph node metastases were seen in 71% of patients with tumor angio or lymphatic invasion versus 17% of patients without (P < .0001). Seventy-five percent of patients with an increased preoperative serum CA 27.29 had lymph node metastases, and the mean levels were greater among patients who were lymph node positive (27 U/ml ± 2 versus 20 ± 1; P = .0002). There was no significant association between any other demographic, histologic, or molecular feature that was investigated and lymph node metastases. Conclusion: We did not identify histologic, demographic, or molecular variables that can exclude the risk of associated lymphatic metastases reliably. Furthermore, not all predictive factors are known before the operation (eg, whether the tumor is T1a or T1b). Therefore, we recommend that SLNB be performed in all patients with clinically lymph node-negative invasive breast cancer.
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