Intra-patient variation between breast cancer axillary lymph node metastases using quantifiable features

Area of Science:

• Oncology
• Pathology
• Cancer Biology

Background:

• Axillary lymph node metastases are critical for breast cancer staging and prognosis.
• Understanding intra-patient heterogeneity in metastases is essential for accurate treatment strategies.

Purpose of the Study:

• To evaluate intra-patient variations in clinically relevant quantifiable features between axillary lymph node metastases in breast cancer.
• To determine if observed variations exceed methodological tolerance limits, indicating true biological differences.

Main Methods:

• Analyzed 44 breast cancer patients with varying numbers of axillary lymph node metastases (2-33 per patient).
• Quantified mitotic figures, volume percentage epithelium, and mean nuclear area within each metastasis.
• Calculated the coefficient of variation (CV) for each feature and compared it to established methodological tolerance limits.

Main Results:

• Significant intra-patient variation was observed: CVs exceeded methodological limits in 86% for mitotic count, 48% for epithelium volume, and 47% for nuclear area.
• These variations are unlikely due to sampling or measurement errors, indicating real biological differences.
• Higher variation correlated positively with the number of lymph node metastases.

Conclusions:

• Considerable biological variation exists in quantifiable features between axillary lymph node metastases within individual breast cancer patients.
• This heterogeneity may stem from independent origins of metastases from different tumor clones or distinct developmental pathways.
• Findings highlight the importance of accounting for tumor heterogeneity in breast cancer management.