What Are The Stages Of Breast Cancer?
Receiving a breast cancer diagnosis often raises many questions about treatment and life after therapy. To determine the most appropriate treatment approach, physicians use a system called staging, which describes how much the cancer has grown or spread. Understanding the stages of breast cancer can help patients make informed decisions about their care.
Understanding breast cancer stage
Breast cancer develops when certain breast cells undergo changes and begin to grow abnormally. Although it can occur in anyone, it primarily affects women, and the risk increases with age.
There are several types of breast cancer. Diagnostic tests allow physicians to identify the specific type of cancer and determine the extent of its progression, referred to as its stage.
How many stages of breast cancer are there?
Breast cancer is classified into five main stages. Physicians refer to these as Stage 0 and Stages I through IV (or Stages 0 to 4).
To describe the characteristics of the cancer more precisely, specialists also use the TNM classification system:
- T (Tumor): the size of the tumor and whether it has extended into nearby tissues, such as the skin or chest wall muscles.
- N (Nodes): whether the cancer has spread to the lymph nodes and to what extent.
- M (Metastasis): whether the cancer has spread beyond the breast to other parts of the body.
In addition, physicians assess the histologic grade, a score ranging from 1 to 3 that describes how closely cancer cells resemble normal cells:
- Grade 1: cells closely resemble normal cells and tend to grow slowly.
- Grade 2: cells have intermediate characteristics.
- Grade 3: cells appear more abnormal and tend to grow more rapidly.
Patients should discuss the specific meaning of their TNM classification and tumor grade with their physician.
What are the 5 stages of breast cancer?
The stage of breast cancer is established at the time of diagnosis. In general, the higher the stage, the more advanced the disease.
Stage 0
The cancer has not spread beyond the breast. This is a non-invasive form of breast cancer known as ductal carcinoma in situ (DCIS), in which abnormal cells remain confined to the milk ducts or lobules.
Stage I
These are generally small tumors that have begun to invade surrounding tissue.
- Stage IA: a small tumor with no lymph node involvement.
- Stage IB: a small tumor, typically less than 2 cm in size, with minimal micrometastases in the lymph nodes.
Stage II
Invasive breast cancers.
- Stage IIA: a tumor up to 2 cm in size with spread to 1 to 3 lymph nodes, or a tumor between 2 and 5 cm without lymph node involvement.
- Stage IIB: a tumor between 2 and 5 cm with spread to 1 to 3 lymph nodes, or a tumor larger than 5 cm without lymph node involvement.
Stage III
All Stage III breast cancers are invasive.
- Stage IIIA: a tumor of any size with spread to 4 to 9 lymph nodes, or a tumor larger than 5 cm with spread to 1 to 3 lymph nodes.
- Stage IIIB: a tumor that has extended to the chest wall or skin, with involvement of up to 9 lymph nodes.
- Stage IIIC: a tumor of any size with spread to 10 or more lymph nodes.
Stage IV
The cancer has spread to distant parts of the body, including other organs. This is known as metastatic breast cancer.
Two tumors of the same size may have very different prognoses depending on their biological characteristics. For this reason, physicians consider not only the size and extent of the disease but also the histologic grade and the status of relevant biological receptors.
Early-stage vs. advanced breast cancer
Early-stage breast cancer generally includes Stages 0 through IIIA. Advanced breast cancer includes Stages IIIB through IV, when the disease has typically spread to the chest wall, skin, or distant organs.
Breast cancers diagnosed at an early stage often respond well to surgery and local treatments. More advanced stages are more likely to require systemic therapies, such as chemotherapy or targeted treatments.
How is breast cancer staged?
Specialists use several tests and procedures to determine the stage of breast cancer.
Imaging Studies
Imaging tests help define the size and location of the tumor:
- Breast MRI (magnetic resonance imaging)
- Breast ultrasound
- Diagnostic mammography
In some cases, additional tests such as CT scans, bone scans, or PET scans may be needed to determine whether the cancer has spread to other parts of the body.
Biopsy
During a biopsy, a physician uses a needle to remove a sample of breast tissue. The tissue is then examined by a pathologist, who confirms the presence of cancer cells and identifies their characteristics.
Biomarker Testing
Analysis of blood samples and tumor tissue can identify proteins and other biomarkers that provide additional information about the cancer, including:
- Hormone receptors (estrogen and progesterone): elevated levels may indicate specific hormone receptor-positive breast cancers.
- HER2: elevated levels indicate HER2-positive breast cancer.
Genetic mutations, genomic testing, PD-L1 status, and other emerging biomarkers are playing an increasingly important role in guiding personalized treatment strategies.
Why is breast cancer staging important?
The information gathered during staging helps physicians develop an individualized treatment plan. Depending on the stage, treatment may include:
- Surgery
- Chemotherapy
- Hormone therapy
- Radiation therapy
- Targeted therapy
A multidisciplinary care team works with each patient to discuss treatment goals and determine the most appropriate options. Some patients can be successfully treated with surgery alone, while others may require radiation therapy, endocrine therapy, or chemotherapy. In metastatic breast cancer, chemotherapy, hormone therapy, and targeted therapies can help improve quality of life and enable many people to live with the disease for years.
Breast cancer staging may also help determine eligibility for participation in clinical trials.
Life after a breast cancer diagnosis
A breast cancer diagnosis can be challenging both for the person receiving it and for those close to them. Understanding the stage of the disease can provide valuable insight and help support informed treatment decisions.
With appropriate medical and psychological support, many people continue to lead fulfilling lives during and after treatment. Healthcare professionals can help patients understand what to expect throughout their care journey and how to navigate it as effectively as possible.
If you have been diagnosed with breast cancer, the multidisciplinary Oncology team at UPMC Salvator Mundi International Hospital is available for a consultation.