What labs are used for breast cancer staging?

Breast Cancer Staging Laboratory Tests and Imaging

The essential laboratory tests for breast cancer staging include complete blood count, liver and renal function tests, alkaline phosphatase, and calcium levels, while imaging should include bilateral mammography and ultrasound of the breast and regional lymph nodes, with additional imaging based on clinical stage and symptoms. 1, 2

Core Laboratory Tests

• Complete blood count (CBC) 1
• Liver function tests 1
• Renal function tests 1, 2
• Alkaline phosphatase 1, 2
• Calcium levels 1, 2

Standard Imaging Studies

Initial Imaging for All Patients

• Bilateral diagnostic mammography 1
• Ultrasound of breast and regional lymph nodes 1
  • Particularly valuable for evaluating axillary involvement (95% detection rate for breast parenchymal lesions) 1
  • Best modality for assessing axillary involvement at initial diagnosis 1

Selective Imaging Based on Clinical Presentation

Breast MRI (Not Routine)

MRI should be considered in specific scenarios:

• Dense breast tissue 1, 2
• Familial breast cancer with BRCA mutations 1, 2
• Breast implants 1
• Lobular cancers 1
• Suspected multifocality/multicentricity 1, 2
• Large discrepancies between conventional imaging and clinical exam 1
• Before and during neoadjuvant chemotherapy 1
• When breast parenchymal lesions are not detected by mammography or ultrasound 1
• Occult primary tumor with positive axillary nodes 1
• Evaluation of chest wall involvement 1

MRI has the highest sensitivity (94.6%) compared to mammography (54.5%) and ultrasound (67.2%) 3, but has limitations including high false-positive rates 1.

Additional Staging Studies for Advanced Disease

For patients with clinical stage T3N1M0, locally advanced disease, or symptoms suggesting metastases:

• Bone scan (category 2B) 1
• Abdominal imaging (CT, ultrasound, or MRI) 1
• Chest imaging (CT or X-ray) 1

These additional studies are not indicated in patients with stage I disease without signs or symptoms of metastatic disease 1.

PET/CT Considerations

• Not recommended for routine staging of early breast cancer 1
• May be useful when conventional methods are inconclusive 1
• More useful for stage IIIB and operable IIIA tumors 1
• Particularly valuable for specific tumor subtypes: invasive ductal cancers, ER-negative, triple-negative, and high-grade malignancies 1
• Can detect distant metastases with sensitivity of 50-100% and specificity of 50-97% in advanced breast cancer 1
• Superior in detecting internal mammary and mediastinal lymphadenopathy 1
• Not as useful for low-grade malignancies or invasive lobular cancer due to low isotope uptake 1

Cardiac Evaluation

• Cardiac function assessment (cardiac ultrasound or MUGA scan) is essential for patients planned for anthracycline and/or trastuzumab treatment 1

Pathological Assessment

• Core needle biopsy (preferred over fine needle aspiration) 1, 2
• Pathological report should include:
  • Histological type and grade
  • Estrogen receptor (ER) status
  • Progesterone receptor (PgR) status
  • HER2 status (by IHC or FISH/CISH)
  • Ki67 or other proliferation marker 1, 2

Staging Algorithm Based on Clinical Presentation

1. All patients: CBC, liver and renal function tests, alkaline phosphatase, calcium, bilateral mammography, breast ultrasound
2. If clinically node-positive: Add ultrasound-guided FNA or core biopsy of suspicious lymph nodes
3. If locally advanced disease (T3N1M0 or higher): Add bone scan, abdominal imaging, chest imaging
4. If symptoms of metastasis: Target imaging to symptomatic areas (bone pain, abnormal liver tests, pulmonary symptoms)
5. If considering neoadjuvant therapy: Consider breast MRI for baseline assessment

Common Pitfalls to Avoid

• Relying solely on mammography in dense breast tissue (sensitivity only ~50% in this population) 4
• Over-reliance on a single imaging modality (no single modality is most accurate for tumor size) 5
• Mammography and ultrasound tend to underestimate tumor size (by 3.5mm and 4mm respectively) 5
• MRI tends to overestimate tumor size (by approximately 3mm) 5
• Performing comprehensive radiological staging in early-stage, asymptomatic patients (low yield, unnecessary radiation exposure) 1
• Using PET/CT for routine staging of early breast cancer (high false-positive rate) 1

Remember that accurate staging is crucial as it directly impacts treatment planning and prognosis 6. The multidisciplinary approach to breast cancer treatment depends on precise staging information to guide surgical, radiation, and systemic therapy decisions 7.