This study is designed to evaluate the feasibility and safety of axillary radiotherapy for early stage breast cancer with limited positive sentinel lymph nodes.

Randomized clinical trials have demonstrated that complete axillary lymph node dissection is not necessary in patients with 1-2 positive sentinel lymph nodes who undergo breast conserving surgery, whole breast irradiation, and systemic therapy. However, whether or not the regional lymph node should be irradiated and if radiation given, whether or not all levels of axillary lymph node and internal mammary and supraclavicular lymph node should be irradiated is unknown. The purpose of this study is to evaluate the feasibility and safety of axillary level I-II areas radiotherapy for early stage breast cancer with 1-2 positive sentinel lymph nodes and no further axillary lymph node dissection.

Inclusion Criteria:

• Female
• 18~70 years old
• Pathologically confirmed invasive breast cancer
• A clinical T1-2N0M0 tumor
• Treated with breast conserving surgery and sentinel lymph node biopsy
• 1~2 positive sentinel lymph nodes, including micro-metastases or macro-metastases.
• ECOG score 1~2
• Written informed consent

Exclusion Criteria:

• Patients underwent complete axillary lymph node dissection
• Patients underwent mastectomy
• Patients underwent neoadjuvant therapy
• Clinically node positive pre-operative
• Sentinel lymph nodes only containing isolated tumour cells (<0.2 mm)
• Prior history of invasive breast cancer or previous or concurrent other malignancies within the past 5 years
• Previous radiation therapy of breast or thorax
• Medical contraindication for radiotherapy
• Prior axillary surgery or radiotherapy
• Unable or unwilling to receive breast conserving surgery or sentinel lymph node biopsy
• Pregnant or nursing

Early stage breast cancer patients with 1~2 positive sentinel lymph nodes