What is the likelihood of a 2mm increase in size of a supraclavicular lymph node, from 6mm to 8mm over one year, being cancerous in a patient with a history of hormone receptor-positive breast cancer and a CHEK2 (Checkpoint Kinase 2) mutation?

Supraclavicular Lymph Node Growth: Cancer Risk Assessment

A supraclavicular lymph node growing from 6mm to 8mm over one year in a patient with hormone receptor-positive breast cancer and CHEK2 mutation warrants immediate tissue diagnosis, as supraclavicular involvement represents N3c disease (stage IV) with significant implications for mortality.

Critical Context: Supraclavicular Nodes in Breast Cancer

Supraclavicular lymph node involvement is classified as N3c disease and indicates metastatic spread, fundamentally changing prognosis and treatment approach. 1

• Any clinically detected ipsilateral supraclavicular lymph node in a breast cancer patient is classified as N3c, regardless of size 1
• N3c disease represents advanced regional spread and is associated with significantly worse outcomes 1
• The 2mm growth over one year suggests active disease progression rather than stable benign adenopathy 1

Risk Factors Specific to This Patient

The combination of hormone receptor-positive breast cancer history and CHEK2 mutation substantially increases the likelihood of malignancy:

• CHEK2 carriers with breast cancer have significantly elevated risk of contralateral breast cancer (10-year cumulative incidence of 13% in premenopausal women, 4% in postmenopausal women) 1
• CHEK2-associated breast cancers are predominantly ER-positive (91.5% hormone receptor-positive in one series) 1, 2
• CHEK2 mutation carriers develop second cancers more frequently than non-carriers 3
• CHEK2 carriers have worse metastasis-free survival compared to non-carriers (64% vs. 84% at 7 years, p=0.045) 4

Size and Growth Pattern Analysis

While 8mm is relatively small, the documented growth from 6mm to 8mm over one year is concerning:

• Normal lymph nodes are typically <10mm in short axis, but any measurable growth warrants investigation 1
• The growth pattern (33% increase over one year) suggests active pathology rather than stable reactive changes 1
• In breast cancer patients, even small supraclavicular nodes require tissue diagnosis due to their prognostic significance 1

Immediate Diagnostic Approach

Tissue diagnosis via fine needle aspiration (FNA) or core needle biopsy of the supraclavicular node is mandatory:

• FNA or core biopsy provides definitive diagnosis with minimal morbidity 1
• PET-CT imaging should be performed to evaluate for additional metastatic disease if biopsy confirms malignancy 5
• Baseline cardiac evaluation (LVEF) is required if systemic therapy is planned 5

Treatment Implications if Malignant

If biopsy confirms metastatic breast cancer, treatment shifts from curative to palliative intent:

• For hormone receptor-positive metastatic disease, endocrine therapy with CDK4/6 inhibitors is first-line treatment 6
• Single-agent chemotherapy is preferred over combination regimens for hormone receptor-positive disease unless immediately life-threatening 6
• Supraclavicular radiation may be considered for local control in select cases 1

Common Pitfalls to Avoid

• Do not assume benign etiology based on size alone - supraclavicular location in breast cancer patients demands tissue diagnosis regardless of size 1
• Do not delay biopsy for serial imaging - documented growth over one year already justifies immediate tissue sampling 1
• Do not overlook CHEK2-associated increased risk - these patients have higher rates of second cancers and worse metastasis-free survival 3, 4
• Do not perform prophylactic salpingo-oophorectomy - CHEK2 mutations confer moderate breast cancer risk but no established ovarian cancer risk 1, 2