Is involvement of the supraclavicular fossa nodes in breast cancer considered stage IV disease?

Supraclavicular Fossa Nodal Involvement in Breast Cancer: Stage IIIC, Not Stage IV

No, supraclavicular fossa nodal involvement in breast cancer is classified as Stage IIIC (N3c) disease, not Stage IV. This represents locally advanced breast cancer that should be treated with curative intent using multimodality therapy, not palliative systemic therapy alone. 1

Current TNM Staging Classification

The AJCC staging system underwent a critical revision in 2002-2003 that fundamentally changed how supraclavicular disease is managed:

• Ipsilateral supraclavicular lymph node metastases are classified as N3c disease 1
• N3c disease combined with any T stage and M0 status equals Stage IIIC breast cancer 1
• This reclassification moved supraclavicular involvement from the previous M1 (Stage IV) designation to regional nodal disease 1, 2

Specific N3 Category Breakdown

The N3 designation encompasses three distinct patterns of advanced regional nodal involvement:

• N3a: Metastases in ipsilateral infraclavicular (level III axillary) lymph nodes 1
• N3b: Metastases in ipsilateral internal mammary nodes with concurrent axillary involvement, or >3 axillary nodes with internal mammary involvement detected by sentinel node biopsy 1
• N3c: Metastases in ipsilateral supraclavicular lymph nodes 1

Evidence Supporting This Reclassification

The rationale for moving supraclavicular disease from Stage IV to Stage IIIC is based on survival outcomes that differ substantially from true distant metastatic disease:

• Patients with supraclavicular involvement treated with multimodality therapy demonstrate 5-year overall survival rates of 68.6%, which is comparable to other Stage IIIC patients rather than Stage IV patients 3
• Survival outcomes are similar whether supraclavicular disease presents at initial diagnosis or as locoregional recurrence 4, 5
• Treatment outcomes justify curative-intent therapy: Studies consistently show that patients with isolated supraclavicular metastases respond more like locally advanced breast cancer than distant metastatic disease 5

Treatment Implications

The Stage IIIC designation fundamentally changes treatment approach:

• Multimodality treatment with curative intent is indicated: This includes systemic chemotherapy, surgery, and comprehensive locoregional radiotherapy 3, 5
• Radiation therapy should include the supraclavicular area, infraclavicular region, chest wall, internal mammary nodes, and any at-risk axillary bed when ≥4 positive axillary nodes are present 1
• Neck dissection of supraclavicular nodes does not improve outcomes and is not routinely recommended 3

Critical Distinction from True Stage IV Disease

While supraclavicular involvement was historically considered M1 disease between 1987-2002, the evidence clearly demonstrates this was inappropriate:

• Patients with supraclavicular-only disease have significantly better outcomes than those with visceral metastases, which led to the 2003 AJCC reclassification 2, 5
• The 5-year disease-free survival of 46.7% and distant metastasis-free survival of 57.0% in supraclavicular disease patients supports aggressive locoregional treatment 3

Common Pitfall to Avoid

Do not confuse ipsilateral supraclavicular involvement (N3c, Stage IIIC) with contralateral axillary involvement, which remains Stage IV disease. 6 Only ipsilateral supraclavicular nodes are considered regional disease; contralateral nodal involvement of any kind remains distant metastatic disease, though some advocate for reclassification of contralateral axillary disease as well. 6