Significance of Lymph Node Evaluation in Breast Cancer Management

Lymph Node Evaluation and Staging

The National Comprehensive Cancer Network recommends that at least 10 lymph nodes should be provided for pathologic evaluation to accurately stage the axilla 1
The number of positive lymph nodes is a critical factor in determining breast cancer staging according to the TNM system (pN1 if 1-3 lymph nodes, pN2 if 4-9 lymph nodes, and pN3 if ≥10 lymph nodes are involved) 3

The National Comprehensive Cancer Network recommends that patients with 4 or more positive lymph nodes should receive postmastectomy radiation therapy to the chest wall and regional lymph nodes (category 1 recommendation) 2, 4, 5
For patients who undergo lumpectomy with 4 or more positive nodes, the National Comprehensive Cancer Network recommends radiation therapy to whole breast with or without boost, plus regional nodal irradiation (category 1) 4, 5, 6
Three randomized clinical trials have shown that disease-free and overall survival advantages are conferred by irradiation of the chest wall and regional lymph nodes in women with 4 or more positive axillary lymph nodes 1, 7
For patients with 1-3 positive lymph nodes after lumpectomy, the National Comprehensive Cancer Network recommends radiation therapy to whole breast with or without boost (category 1); strongly consider regional nodal irradiation based on risk estimate 4, 5, 6

Regional nodal irradiation includes treatment of the supraclavicular area, infraclavicular region, internal mammary nodes, and any part of the axillary bed considered at risk 4, 5
The MA.20 and EORTC 22922 trials demonstrated that after 10 years of median follow-up, regional nodal irradiation improved locoregional disease-free survival, distant disease-free survival, and breast cancer mortality, but not overall survival 4, 5

For invasive tumors that are 1 cm or smaller in diameter and tumors of favorable histologic type, removal of level I nodes may be adequate 8
For staging purposes, removal of level I and level II nodes permits an accurate assessment of axillary nodal status 8

The presence of 4 or more positive lymph nodes places patients at substantially increased risk for locoregional recurrence of disease 1
Prophylactic chest wall irradiation in patients with 4 or more positive nodes substantially reduces the risk of local recurrence 1
Omitting regional nodal irradiation in patients with 4 or more positive nodes can lead to poor locoregional control and decreased survival 1, 2, 4