What is the TNM (Tumor, Node, Metastasis) grade of locally advanced breast carcinoma?

TNM Classification of Locally Advanced Breast Carcinoma

Locally advanced breast carcinoma corresponds to Stage III disease in the TNM staging system, which encompasses T3N1M0 (Stage IIIA), as well as T4 tumors with any N status, or any T with N2-N3 nodal involvement (Stages IIIA, IIIB, and IIIC), all without distant metastases (M0). 1

Primary Tumor (T) Classification in Locally Advanced Disease

The T stage for locally advanced breast cancer includes:

• T3: Tumor >50 mm in greatest dimension 1
• T4a: Extension to the chest wall, not including only pectoralis muscle adherence/invasion 1
• T4b: Ulceration and/or ipsilateral satellite nodules and/or edema (including peau d'orange) of the skin, which do not meet criteria for inflammatory carcinoma 1
• T4c: Both T4a and T4b 1
• T4d: Inflammatory carcinoma 1

Regional Lymph Node (N) Classification in Locally Advanced Disease

The nodal involvement that defines locally advanced disease includes:

• N1: Metastases to movable ipsilateral level I, II axillary lymph node(s) 1
• N2a: Metastases in ipsilateral level I, II axillary lymph nodes that are clinically fixed to one another (matted) or to other structures 1
• N2b: Metastases only in clinically detected ipsilateral internal mammary nodes in the absence of clinically evident axillary lymph node metastases 1
• N3: Metastases to ipsilateral infraclavicular nodes, or ipsilateral internal mammary nodes with axillary involvement, or ipsilateral supraclavicular nodes 1

Stage Groupings for Locally Advanced Disease

Stage IIIA includes:

• T3N1M0 (operable locally advanced disease) 1
• T0-2, N2, M0 1
• T3N2M0 1

Stage IIIB includes:

• T4N0-2M0 (inoperable locally advanced disease) 1

Stage IIIC includes:

• Any T, N3, M0 1

Clinical Distinction: Operable vs. Inoperable

A critical distinction exists within Stage III disease based on operability 1:

• Operable locally advanced disease (T3N1M0): Initial surgical approach is likely to achieve pathologically negative margins and provide long-term local control; treatment follows standard Stage II protocols 1

• Inoperable locally advanced disease (Stage IIIA except T3N1M0, IIIB, or IIIC): Initial surgical approach is unlikely to remove all disease or provide long-term local control; requires neoadjuvant chemotherapy before definitive surgery 1

Required Staging Workup for Locally Advanced Disease

For patients with locally advanced breast cancer, comprehensive staging must include 1, 2:

• History and physical examination 1, 2
• Complete blood count, platelet count, liver function tests, and alkaline phosphatase 1
• Chest imaging (X-ray or CT) 1, 2
• Abdominal imaging with CT, ultrasound, or MRI 1, 2
• Bone scan 1, 2
• Diagnostic bilateral mammogram 1, 2
• Pathology review with ER/PR and HER2 status determination 1, 2
• Genetic counseling if high-risk for hereditary breast cancer 1, 2

Important caveat: PET or PET/CT scans should generally be discouraged for evaluating Stage III disease, except when other staging studies are equivocal or suspicious, as biopsy of suspicious sites provides more useful staging information 1