Objective:

To develop a nomogram for predicting axillary lymph node metastasis (ALNM) in patients with invasive breast cancer (IBC) to inform treatment choices.

Key Findings:

• ALNM rates were 31.4% in the training group and 27.4% in the validation group.
• Independent risk factors for ALNM included tumor size, circumscribed margin, ultrasonic lymph node status, WBC, ER, and BI-RADS.
• The nomogram showed modest predictive performance with AUCs of 0.741 (training) and 0.705 (validation).
• Ultrasonic lymph node status alone had lower AUCs of 0.620 (training) and 0.627 (validation).

Interpretation:

The nomogram has moderate discriminative ability and cannot replace standard axillary staging procedures.

Limitations:

• The model's moderate discriminative ability limits its use as a standalone tool for clinical decision-making.
• The study's retrospective design may introduce biases.

Conclusion:

The nomogram can support preoperative risk stratification for ALNM in IBC patients.