When someone is diagnosed with breast cancer, one of the first things doctors do is determine the stage of the cancer. You may know that staging is important because it helps determine the severity of the cancer and the odds of survival. But staging also allows doctors to develop a more personalized treatment plan tailored to the patient that accounts for factors like tumor size and whether it has spread to other parts of the body. And for patients interested in participating in clinical trials, staging helps doctors determine which trials could be beneficial.
Here, BCRF outlines how breast cancer is staged and what each stage means.
There are several cancer staging systems, and the one doctors use depends on the type of cancer the patient has. For those with breast cancer, that is usually the American Joint Committee on Cancer (AJCC) tumor, node, metastasis (TNM) system. The most recent version includes pathological and clinical staging systems.
The pathological (or surgical) stage is established by examining breast tissue removed during surgery. If surgery cannot be performed soon—or at all—doctors will assign the cancer a clinical stage, which is based on information obtained from a physical exam, imaging tests, and biopsy. Pathological staging is more accurate than the clinical staging because the cancer may have spread beyond the clinical stage estimate.
Doctors use the following pieces of information to determine both pathological and clinical staging:
A note on survival rates that follow: Several variables affect survival rates in breast cancer patients, including age, tumor size, cancer subtype, choice of treatment, and a patient’s ability to care for themselves (performance status). And for those with stage 4 breast cancer, the location of the metastases also plays a role in survival rates. Survival rates mentioned below are averages and do not necessarily reflect survival rates for individual patients.
Stage 0 breast cancer, or ductal carcinoma in situ (DCIS), is an early, pre-invasive (or pre-cancer) form of breast cancer. In DCIS, abnormal cells line the milk ducts in the breast but have not invaded the surrounding breast tissue. That sounds frightening, but almost all women with this precursor to breast cancer can be cured. However, DCIS does raise a person’s risk of developing invasive breast cancer (where the cancer cells move beyond the milk ducts), so it’s still a serious concern. At this time, there is no way to identify which cases of DCIS could become invasive breast cancer, so it’s almost always treated.
This is the earliest stage of invasive breast cancer. The tumor is small and located in the patient’s breast tissue, nearby lymph nodes, or both. Stage 1 is subdivided into stages 1A and 1B. In 1A, the size of the tumor is less than 2 centimeters (cm) in diameter and has not spread to the lymph nodes. In 1B, the tumor is also less than 2 cm, but cancer cells have spread to a very small number of lymph nodes. Or, for some patients with 1B, there is no sign of a primary breast tumor, only small clusters of cancer cells (micro-metastases) in the lymph nodes.
The prognosis for stage 1 breast cancer is excellent, which is why early detection is so important. The five-year survival rate—the number of patients who are alive five years after diagnosis—is 99 percent.
Stage 2 breast cancers are larger than stage 1 breast cancers but are still limited to the breast or nearby lymph nodes (those in the armpit and close to the breastbone and collarbone). Like stage 1 breast cancer, stage 2 is divided into A and B stages. Breast cancer is in stage 2A if:
Stage 2B means that:
The five-year survival rate for patients with stage 2 breast cancer is 93 percent.
The tumor is larger now or has spread to nearby tissues, such as the skin covering the breast or the muscle underneath, or it has spread to several nearby lymph nodes. There are three subcategories of stage 3 breast cancer:
Stage 3A:
Stage 3B:
Stage 3C:
Stage 3 breast cancer has a five-year survival rate of 86 percent.
A diagnosis of stage 4 breast cancer, or metastatic breast cancer (MBC), means the malignant cells have left the primary site in the breast or nearby lymph nodes. The cells travel to distant organs—most often the bones, liver, lungs, and/or brain—via the bloodstream and lymphatic system and begin to grow there. Thanks to research, the FDA has approved 11 new treatments for metastatic breast cancer—based on the findings of BCRF investigators and others—since 2016, but the disease cannot be cured. Stage 4 breast cancer is the leading cause of breast cancer death.
How long someone diagnosed with stage 4 will live varies significantly. The 5-year-survival rate is 31.9 percent, though some people do live longer: A study published in Epidemiology in 2016 found that 13 percent of women with MBC were alive 10 years after their diagnosis.
There is another staging system that defines the location of the cancer. It’s usually used by cancer registries such as National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program, but doctors sometimes use these terms as well.
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Stages of breast cancer | Understand breast Cancer staging. (n.d.). American Cancer Society. https://www.cancer.org/cancer/types/breast-cancer/understanding-a-breast-cancer-diagnosis/stages-of-breast-cancer.html
Survival rates for breast cancer. (n.d.). American Cancer Society. https://www.cancer.org/cancer/types/breast-cancer/understanding-a-breast-cancer-diagnosis/breast-cancer-survival-rates.html
Treatment of ductal carcinoma in situ (DCIS). (n.d.). American Cancer Society. https://www.cancer.org/cancer/types/breast-cancer/treatment/treatment-of-breast-cancer-by-stage/treatment-of-ductal-carcinoma-in-situ-dcis.html
UpToDate. (n.d.). UpToDate. https://www.uptodate.com/contents/tumor-node-metastasis-tnm-staging-classification-for-breast-cancer
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