A nomogram for predicting three or more axillary lymph node involvement before breast cancer surgery

Area of Science:

• Oncology
• Radiology
• Surgical Pathology

Background:

• The American College of Surgeons Oncology Group (ACOSOG)-Z0011 established criteria for omitting sentinel lymph node biopsy in certain breast cancer patients.
• Previous nomograms identified patients not requiring intraoperative frozen sections for sentinel lymph node evaluation.
• The need for improved predictive tools using advanced imaging modalities persists.

Purpose of the Study:

• To validate and enhance a nomogram for identifying patients with clinical T1-2, node-negative invasive breast cancer who do not require intraoperative sentinel lymph node analysis.
• To assess the diagnostic performance of the nomogram utilizing ultrasonography (US) and positron emission tomography/computed tomography (PET/CT).
• To determine the nomogram's utility in selecting candidates for neoadjuvant chemotherapy.

Main Methods:

• A nomogram was developed based on factors associated with three or more axillary lymph node metastases in a training set of 1030 patients.
• The nomogram was validated on a separate set of 781 patients.
• The nomogram's performance was evaluated on 1067 patients meeting ACOSOG-Z0011 criteria, using US and PET/CT findings.

Main Results:

• The nomogram demonstrated strong predictive accuracy with an area under the receiver operating characteristic curve (AUC) of 0.856 in the training set and 0.866 in the validation set.
• Multivariate analysis identified larger tumor size, higher ultrasonographic ALN classification grade, and suspicious PET/CT findings as significant predictors.
• When applied to 1067 patients, the nomogram correctly identified 90 (8.4%) patients with high risk, achieving 93.8% specificity and 96.4% negative predictive value, with a 3.8% false-negative rate.

Conclusions:

• The upgraded nomogram, incorporating US and PET/CT, significantly improves the prediction of sentinel lymph node positivity in early-stage breast cancer.
• This tool effectively identifies patients who can safely forgo intraoperative analysis of sentinel lymph nodes.
• The nomogram's accuracy supports its use in clinical decision-making, including patient selection for neoadjuvant chemotherapy.