Once your healthcare team diagnoses triple-positive breast cancer (TPBC), you may have tests to learn how far the cancer has spread. This process is called staging.
Complete information about your cancer's stage may not be available until after breast cancer surgery.
Tests and procedures used to stage TPBC may include:
Not everyone needs all of these tests. Your healthcare team picks the tests based on your specific situation.
Information used in staging includes:
- The size of the cancer in the breast.
- Whether cancer cells have spread to the lymph nodes or other parts of the body.
- The cancer's grade.
- The cancer's hormone receptor status.
- The cancer's HER2 status.
- The presence of certain genes that might affect treatment options.
- Other pieces of information that may become available after the cancer is removed during surgery.
Types of staging
The process of breast cancer staging can take place at different times after diagnosis and around treatment. Your stage may change as your care team gets more information about your cancer.
Healthcare professionals use different types of stages at different times. This may include:
- Anatomic staging happens after a breast biopsy confirms cancer. It tells your care team about the size of the cancer and whether it has spread. It does not take cancer grade, hormone receptor status or HER2 status into account.
- Clinical prognostic staging uses the test results available before treatment, including grade, hormone receptor status and HER2 status, to help plan care.
- Pathological prognostic staging is used after surgery once the cancer is removed. This kind of staging looks at factors such as the size of the cancer removed during surgery and the number of lymph nodes removed that contain cancer.
- Postneoadjuvant therapy prognostic staging or staging after treatment given before surgery describes the cancer after that treatment and helps plan next steps.
Because there are several types of stages that consider different factors, the stages of breast cancer can be confusing and complicated. Ask your healthcare team to explain your stage and what it means for your treatment.
Anatomic stages
Anatomic staging is the simplest form of breast cancer staging. To decide on the anatomic stage, the healthcare team uses the size of the cancer and whether it has spread. Using this type of staging, the stages go from 0 to 4.
- Stage 0. Cancer cells have not spread.
- Stage 1. The cancer in the breast is less than 1 inch (2 centimeters) in diameter. Cancer cells have spread beyond ducts into the breast tissue. There is little or no evidence of cancer in the lymph nodes. Cancer has not spread elsewhere in the body.
- Stage 2. The cancer in the breast is less than 2 inches (5 centimeters) in diameter and has spread to some underarm lymph nodes.
- Stage 3. The cancer in the breast is any size and has spread to many underarm lymph nodes. Or the cancer is larger than 2 inches (5 centimeters) in diameter and has spread to some underarm lymph nodes. This stage also includes cancers that spread to the skin, the chest beyond the muscle or the lymph nodes inside the chest wall. Inflammatory breast cancer is considered a stage 3 cancer.
- Stage 4. The cancer in the breast is any size, and cancer cells have spread to sites away from the breast and nearby lymph nodes. These sites may include the brain, bones, lungs or liver.
The anatomic stage may be the first stage your healthcare team talks about after your diagnosis. The stage may change as your team gets more information about your cancer, such as the hormone receptor status.
Grades
A cancer's grade is a number that tells the healthcare team how different the cancer cells look from healthy cells. The grades of breast cancer, including triple-positive breast cancer, go from 1 to 3.
To decide on the grade, doctors in the lab, called pathologists, use a microscope to look at the cancer cells from a biopsy. If the cancer cells look similar to healthy cells, then the cancer cells are low grade. Low-grade cancer grows slowly. If the cancer cells look very different from healthy cells, then the cancer cells are high grade. High-grade cancer grows quickly.
The grades include:
- Grade 1. Grade 1 is a low grade. The cancer cells look similar to healthy cells. Grade 1 typically grows slowly and has a low risk of spreading. It's sometimes called well-differentiated cancer.
- Grade 2. Grade 2 is an intermediate grade. The cancer cells look a little different from healthy cells. Grade 2 grows more quickly than grade 1 cancer. It also has a higher risk of spreading. Sometimes it's called moderately differentiated cancer.
- Grade 3. Grade 3 is a high grade. The cancer cells look very different from healthy cells. Grade 3 is considered a fast-growing cancer. It has the highest risk of spreading. Sometimes it's called poorly differentiated cancer.
The grade of triple-positive breast cancer helps the healthcare team understand the prognosis and make a treatment plan.
Aug. 28, 2026