What is the process for staging breast cancer and determining treatment options?

Breast Cancer Staging and Treatment Determination

The process for staging breast cancer involves clinical examination, radiological investigations, and pathomorphological assessment, followed by a multidisciplinary approach to determine appropriate treatment options based on disease stage, tumor biology, and patient factors. 1

Initial Diagnostic Workup

• Diagnosis begins with clinical examination, bilateral diagnostic mammography, and breast ultrasound; MRI may be used in specific cases 1
• Pathologic diagnosis should be obtained before any surgical procedure using fine needle aspiration or core needle biopsy 1
• Final pathological diagnosis should follow the World Health Organization classification and TNM staging system 1

Comprehensive Staging Process

Clinical and Pathological Assessment

• TNM staging evaluates tumor size (T), nodal involvement (N), and presence of metastasis (M) 1
• Significant changes in the staging system include:
  • Distinction between micrometastases and isolated tumor cells in lymph nodes 1
  • Classification of lymph node involvement based on number of affected nodes 1
  • Reclassification of infraclavicular and supraclavicular node involvement 1

Biomarker Testing (Essential for Treatment Planning)

• Determination of estrogen receptor (ER) and progesterone receptor (PR) status is mandatory, preferably by immunohistochemistry 1
• HER2 status determination is required, with ambiguous immunohistochemistry results (2+) requiring confirmation by in situ hybridization (FISH or CISH) 1, 2
• Reports should include percentage of hormone receptor-positive cells 1
• HER2 testing should only be performed in accredited laboratories with established standardized procedures 1

Imaging for Staging

• Routine staging examinations include physical examination, complete blood count, and liver function tests 1

• For higher-risk patients (≥4 positive axillary nodes, T4 tumors, or suspicious signs/symptoms), additional imaging is appropriate: 1

  • Chest X-ray
  • Abdominal ultrasound
  • Bone scan

• MRI may be considered in specific situations: 1

  • Mammographically occult tumors
  • Very dense breast tissue
  • Evaluation of multifocal/multicentric disease
  • Assessment before and after neoadjuvant therapy
  • Evaluation of chest wall involvement

Breast Cancer Classification for Treatment Planning

Anatomical Classification

• Stage 0: Pure noninvasive carcinomas (LCIS, DCIS) 1
• Stage I, II, and some IIIA: Operable, local-regional invasive carcinoma 1
• Stage IIIB, IIIC, and some IIIA: Inoperable locoregional invasive carcinoma 1
• Stage IV: Metastatic disease 1

Risk Stratification

• Treatment decisions are based primarily on endocrine responsiveness and secondarily on risk of recurrence 1
• Risk stratification includes three groups: low, intermediate, and high risk 1
• Vascular invasion is an important prognostic factor, particularly in node-negative disease 1

Treatment Approach Based on Staging

Early-Stage Disease (Stage I-II)

• For operable disease, options include breast-conserving surgery with radiation or mastectomy 1
• Sentinel lymph node biopsy is standard for clinically node-negative patients 3
• Systemic therapy decisions are based on tumor biology (hormone receptor and HER2 status) 1
• For small triple-negative tumors (<5mm), surgical excision alone may be appropriate, though many experts recommend adjuvant chemotherapy 3

Locally Advanced Disease (Stage II-III)

• Neoadjuvant chemotherapy is preferred for stage II-III triple-negative breast cancer 3
• Dose-dense anthracycline and taxane-based regimens are preferred for neoadjuvant treatment 3
• For HER2-positive disease, trastuzumab is indicated for adjuvant treatment 2
• Post-mastectomy radiation therapy should be considered for patients with positive lymph nodes or close/positive margins 3

Special Considerations

• For patients with germline BRCA1/2 mutations and HER2-negative triple-negative breast cancer, adjuvant olaparib for 1 year should be considered 3
• Patients with metastatic HER2-positive breast cancer may benefit from trastuzumab in combination with paclitaxel or as a single agent after prior chemotherapy 2

Common Pitfalls in Breast Cancer Staging

• Incomplete pathology reporting can significantly impact treatment decisions; standardized reporting protocols are essential 1
• False-positive and false-negative HER2 test results are common; testing should only be performed in accredited laboratories 1
• Overuse of imaging studies in early-stage disease with no signs/symptoms of metastasis is unnecessary and costly 1, 4
• MRI has a high percentage of false-positive findings; patients should not be denied breast-conservation therapy based on MRI findings alone without tissue sampling 1