Overview

The purpose of this study is to validate whether clinically low-risk, and RecurIndex high-risk N1 patients receiving regional lymph node radiotherapy can further improve clinical outcomes.

Eligibility

Inclusion Criteria:

• Age ≥ 18 years old, ≤ 70 years old.
• Eastern Cooperative Oncology Group (ECOG) ≤ 2.
• Postoperative pathology is clearly diagnosed as invasive breast cancer.
• Meet the clinical definition of low risk: ①Axillary lymph node micrometastasis (N1mic) or ②N1 patients who meet the following conditions at the same time, a）Age ≥ 40 years old, b）Vascular tumor thrombus (LVI) negative or allow few positive LVI (excluding extensive or massive LVI), c）Three subtypes are allowed (Lumina A, Lumina B/HER2 negative, Lumina B/HER2 positive) , namely ER positive (ER ≥ 1%), HER2 negative (HER2 expression negative or + by IHC, or 2+ but negative by FISH) or ER positive (ER ≥ 1%), HER2 positive (3+ by IHC, or 2+ but positive by FISH).
• Postoperative pathological diagnosis of axillary lymph node status is any of the following: a. Sentinel lymph node biopsy or axillary lymph node dissection for micrometastasis (N1mic), b. Sentinel lymph node biopsy for 1-2 lymph node macrometastasis (N1sln), c. Sentinel lymph node biopsy + axillary lymph node dissection or simple axillary lymph node dissection for 1-3 lymph node metastasis (N1).
• The primary tumor and breast undergo breast-conserving surgery or total resection ± breast reconstruction (autologous/prosthetic).
• There must be adequate systemic examination (such as chest X-ray, B-ultrasound, CT, etc.) within 3 months before randomization of radiotherapy to confirm that there is no distant metastasis.
• No contralateral breast cancer must be confirmed by molybdenum target and/or MRI within 12 months before randomization of radiotherapy.
• At least 4 courses of adjuvant chemotherapy with anthracycline or taxane should be completed after surgery.
• Radiotherapy must be performed sequentially after the completion of adjuvant chemotherapy, starting no later than 8 weeks after the end of chemotherapy.
• The patient must have sufficient primary fresh frozen specimens or post-paraffin tissue sections for RecurIndex testing.
• No previous history of malignant tumors, except for basal cell carcinoma of the skin.
• Signed an informed consent form.

Exclusion Criteria:

• Postoperative radiotherapy was confirmed as T3-4, N0, N2-3, M1 lesion staging before enrollment.
• Receive any new adjuvant therapy before surgery, including chemotherapy, endocrine therapy, targeted therapy or radiation therapy.
• Patients who underwent total mastectomy and only sentinel lymph node biopsy.
• Have a history of contralateral breast cancer.
• History of chest radiotherapy.
• combined with severe heart, lung, liver, kidney, hematopoietic, neurological diseases, and mental illness.
• History of autoimmune diseases such as scleroderma or active lupus erythematosus.
• pregnant and lactating patients.
• Unable or unwilling to sign an informed consent form.