Stage III breast cancer is locally advanced disease involving larger tumors, chest-wall or skin invasion, or extensive regional lymph node spread. Modern care combines systemic therapy (often given before surgery), surgery, radiation, and targeted or endocrine treatments guided by tumor biology. Reconstruction and survivorship planning are integral, while high-dose stem cell transplantation is no longer a standard approach.
What is stage III breast cancer?
Stage III breast cancer describes locally advanced disease that has grown beyond the original tumor site into nearby tissues or multiple regional lymph nodes but has not spread to distant organs. Modern staging groups this as IIIA, IIIB and IIIC based on tumor size, skin or chest-wall involvement, and the extent of regional nodal spread.
Subtypes at a glance
- Stage IIIA: Larger tumors or cancers that have spread to several nearby lymph nodes but without chest-wall invasion.
- Stage IIIB: Cancer that extends to the chest wall or causes skin changes (including ulceration or satellite nodules); includes inflammatory breast cancer.
- Stage IIIC: Cancer of any primary size with more extensive regional lymph node involvement (for example, infraclavicular or supraclavicular nodes).
How doctors approach treatment
Care is individualized and planned by a multidisciplinary team (surgical oncology, medical oncology, radiation oncology, plastic surgery, radiology and pathology). Treatment goals are to control the local tumor, treat microscopic disease, and reduce risk of recurrence.
Systemic therapy first
Many patients with stage III disease receive neoadjuvant (preoperative) chemotherapy to shrink the tumor and assess response. Systemic therapy can include cytotoxic chemotherapy and, when indicated, targeted drugs (for example, HER2-directed agents) or immunotherapy for select triple-negative cancers.
Surgery and radiation
After systemic therapy, surgeons determine whether breast-conserving surgery is possible or whether mastectomy is required. Axillary surgery (sentinel node biopsy or axillary dissection) treats regional nodes. Radiation therapy commonly follows surgery to improve local control, especially when nodes or chest wall are involved.
Endocrine and targeted adjuvant treatments
If the tumor is hormone receptor-positive, patients typically receive several years of endocrine therapy after surgery. HER2-positive cancers receive HER2-targeted drugs as part of neoadjuvant and/or adjuvant therapy. Additional targeted agents or adjuvant treatments may be recommended based on genomic testing and risk features.
Reconstruction and survivorship
Breast reconstruction - using implants or the patient's own tissue - is widely available and can be done at the time of mastectomy or later. Survivorship care addresses rehabilitation, lymphedema prevention, psychosocial support and surveillance.
What is no longer routine
High-dose chemotherapy with bone marrow or peripheral stem cell transplantation is not a standard treatment for breast cancer today and is rarely used outside of clinical trials.
Clinical trials and palliative care
Clinical trials remain important for improving outcomes in stage III disease. When disease or symptoms cannot be controlled, palliative care focuses on symptom relief and quality of life.
- Confirm current guideline language and exact criteria for AJCC staging subcategories (IIIA/IIIB/IIIC) in the latest AJCC manual.
- Verify which immunotherapy and targeted agents are approved and recommended for specific stage III subgroups (for example, pembrolizumab in high-risk triple-negative disease and current HER2 regimens).