What is the treatment approach for breast cancer?

Treatment Approach for Breast Cancer

The treatment of breast cancer requires a multidisciplinary approach including surgery, radiation therapy, and systemic therapy, with specific regimens determined by tumor biology, stage, and receptor status. 1, 2

Diagnostic Workup and Staging

• Comprehensive pathologic diagnosis should be obtained via core needle biopsy before any surgical procedure, following the World Health Organization classification and TNM staging system 3, 2
• Mandatory determination of estrogen receptor (ER), progesterone receptor (PR), and HER2 status through immunohistochemistry, with ambiguous HER2 results (2+) requiring confirmation by in situ hybridization 1, 2
• Routine staging examinations include physical examination, complete blood count, and liver function tests 1
• For higher-risk disease (T4 tumors, ≥4 positive nodes), additional imaging is recommended: chest X-ray, abdominal ultrasound, and bone scan 1

Treatment Based on Breast Cancer Subtype

Hormone Receptor-Positive Breast Cancer

• Primary treatment includes surgery (breast-conserving surgery with radiation or mastectomy) 1
• Adjuvant endocrine therapy is mandatory for 5-10 years 1, 4
• Tamoxifen is indicated for premenopausal women and can reduce breast cancer recurrence by 43% 5, 4
• Aromatase inhibitors are preferred for postmenopausal women 1, 4

HER2-Positive Breast Cancer

• Treatment includes surgery plus systemic therapy with HER2-targeted agents 1, 6
• Trastuzumab is indicated for both early-stage and metastatic HER2-positive breast cancer, typically combined with chemotherapy 6, 7
• Careful cardiac monitoring is required during trastuzumab treatment due to risk of cardiomyopathy 6

Triple-Negative Breast Cancer

• Neoadjuvant chemotherapy is preferred before surgery for stage II-III disease 8, 7
• Dose-dense anthracycline and taxane-based regimens are standard treatment 8, 9
• For patients with germline BRCA1/2 mutations, adjuvant PARP inhibitors should be considered 8, 4

Surgical Approach

• Options include breast-conserving surgery with radiation or mastectomy 1
• Contraindications to breast-conserving surgery include multicentric tumors, large tumors (>3-4 cm) in small breasts, retroareolar localization, and tumor-involved margins after resection 1
• Sentinel lymph node biopsy is standard for clinically node-negative patients 1, 8
• Axillary lymph node dissection is recommended for patients with positive sentinel nodes 1, 8

Radiation Therapy

• Breast radiotherapy is strongly recommended after breast-conserving surgery 1
• Post-mastectomy radiotherapy is recommended for patients with four or more positive axillary nodes 1
• Radiation is also suggested for T3 tumors independent of nodal status 1

Systemic Therapy

Neoadjuvant (Preoperative) Therapy

• Preferred for locally advanced disease, triple-negative and HER2-positive subtypes 2, 8
• Allows for assessment of treatment response and potential downstaging of tumors 2, 4

Adjuvant (Postoperative) Therapy

• Endocrine therapy for hormone receptor-positive disease 1
• HER2-targeted therapy plus chemotherapy for HER2-positive disease 1, 6
• Chemotherapy alone for triple-negative disease 8, 7

Special Situations

Ductal Carcinoma In Situ (DCIS)

• Treatment includes breast-conserving surgery with radiation or mastectomy 1
• Tamoxifen is indicated for ER-positive DCIS and can reduce invasive breast cancer risk by 43% 1, 5

Metastatic Breast Cancer (Stage IV)

• Treatment goals shift to prolonging life and palliating symptoms 10, 7
• Therapy is determined by subtype: endocrine therapy with targeted agents for hormone-positive, anti-HER2 therapy for HER2-positive, and chemotherapy for triple-negative 7, 4
• Median overall survival varies significantly by subtype: approximately 5 years for hormone-positive and HER2-positive vs. 1 year for triple-negative 7

Common Pitfalls and Considerations

• Incomplete pathology reporting can significantly impact treatment decisions; standardized reporting protocols are essential 2
• False-positive and false-negative HER2 test results are common; testing should only be performed in accredited laboratories 1, 2
• Cardiac monitoring is critical during trastuzumab therapy due to risk of cardiomyopathy, especially when combined with anthracyclines 6
• Patient participation in clinical trials should be encouraged as breast cancer treatment continues to evolve 1