Lymph Node Status in Breast Cancer Does Not Predict Tumor Biology

Area of Science:

• Oncology
• Genomics
• Breast Cancer Research

Background:

• The 21-gene Oncotype DX Breast Recurrence Score (RS) assay is validated for node-negative, ER+/HER2- breast cancer.
• Its prognostic role in node-positive breast cancer is less understood.

Purpose of the Study:

• To compare RS results in node-negative (N0), micrometastatic (N1mi), and macrometastatic (N+) breast cancer patients.
• To determine if lymph node metastasis is linked to more aggressive tumor biology via RS.

Main Methods:

• Analysis of 610,350 tumor specimens from February 2004 to August 2017.
• Central histology classification and local lymph node status determination.
• Comparison of RS distribution (low, intermediate, high) across different nodal statuses.

Main Results:

• Eighty percent of patients were N0, 4% N1mi, 9% N+, and 7% had unknown nodal status.
• Mean RS was similar across groups (16.7-18.9).
• High RS (≥31) rates were comparable: 10% in N0, 7% in N1mi, and 8% in N+.

Conclusions:

• RS distribution is similar in N0, N1mi, and N+ patients, indicating a biological spectrum.
• This suggests potential chemotherapy benefits exist across node-negative and node-positive ER+/HER2- breast cancer patients.
• Findings may help spare chemotherapy for N+ patients with low RS if RxPONDER trial confirms no benefit.