Predictors of axillary lymph node metastasis in T₁ breast carcinoma

This study was designed to determine the predictors of axillary lymph node metastasis in T1a (≤0.5 cm), T1b (>0.5 cm and ≤1.0 cm), and T1c (>1.0 cm and ≤2.0 cm) breast cancers. The charts of 204 patients who underwent axillary lymph node dissections for T₁ breast carcinomas at our institution were reviewed. Of these, 23 (11%) patients had T1a cancers, 55 (27%) patients had T1b cancers, and 126 (62%) patients were diagnosed with T1c lesions. Fifty patients (24.5%) had axillary node metastases. Of those with T1a lesions, one (4.3%) patient had axillary node involvement, compared with 9 (16.4%) patients with T1b and 40 (31.7%) patients with T1c lesions. Nodal involvement was significantly increased in T1c cancer compared with either T1a (odds ratio = 8.24; P < 0.05) or T1b (odds ratio = 2.73; P < 0.05). Similar results were found in tumors with grade 3 nuclear pleomorphism (odds ratio = 10.45 versus grade 1 and 3.46 versus grade 2; P < 0.05). The presence of lymphovascular invasion was also associated with an increased likelihood of nodal involvement (odds ratio = 3.15; P < 0.05). Predictors of axillary lymph node metastasis in T₁ breast carcinomas include increasing tumor size, grade 3 nuclear pleomorphism, and the presence of lymphovascular invasion. These predictors may have a role in stratifying patients with T₁ breast carcinomas into subgroups that may benefit from less invasive methods of evaluating axillary lymph node status.