Infiltrating breast carcinoma smaller than 0.5 centimeters: is lymph node dissection necessary?

Area of Science:

• Oncology
• Pathology
• Surgical Oncology

Background:

• Incidence of axillary lymph node metastases in small breast carcinomas (≤1.0 cm) varies widely in literature.
• Tumors ≤0.5 cm have shown 0% metastasis, while all tumors ≤1.0 cm show up to 27.1% metastasis.

Purpose of the Study:

• To determine the incidence of axillary lymph node metastases in infiltrating breast carcinomas measuring 1.0 cm or smaller.
• To identify indicators correlating with lymph node metastases in these tumors.

Main Methods:

• Retrospective review of 117 infiltrating breast carcinoma cases (≤1.0 cm) with axillary lymph node dissections.
• Evaluation of tumor characteristics including size, histologic type, grade, receptor status, ploidy, S-phase fraction, and angiolymphatic invasion.
• Immunohistochemical staining for basement membrane components (laminin, Type IV collagen) in metastatic and non-metastatic tumors.

Main Results:

• Overall incidence of axillary lymph node metastases was 10.3% (12/117 cases).
• No lymph node metastases were found in tumors ≤0.5 cm (24 cases).
• Carcinomas measuring 0.6-1.0 cm had a 12.9% metastasis rate (12/93 cases); high nuclear grade correlated significantly (P=0.007).

Conclusions:

• Infiltrating breast carcinomas ≤0.5 cm are unlikely to have axillary lymph node metastases, suggesting dissections may be unnecessary.
• Nuclear grade appears to be the most reliable predictor of lymph node metastases in T1b tumors (0.6-1.0 cm).
• Further investigation into basement membrane components did not reveal a correlation with axillary lymph node metastases.