Once a person is determined to have a malignant tumor or is diagnosed with breast cancer, tests are done to find out if cancer cells have spread within the breast or to other parts of the body.

The process used to find out whether the cancer has spread is called staging. The information gathered from the staging process determines the stage of the disease.

It is important to know the stage in order to plan treatment. The results of some of the tests used to diagnose breast cancer are also used to stage the disease.

Determining the stage of breast cancer

In breast cancer, stage is based on the size and location of the primary tumor, the spread of cancer to nearby lymph nodes or other parts of the body, tumor grade, and whether certain biomarkers are present.

The TNM system, the grading system and the biomarker status are combined to find out the breast cancer stage.

TNM system: used to describe the size of the primary tumor and the spread of cancer to nearby lymph nodes or other parts of the body. TNM stands for tumor (size and location), lymph node (size and location of lymph nodes where cancer has spread) and metastasis (when cancer spreads).

Grading system: The tumor grading system is used to describe how quickly a breast tumor is likely to grow and spread.

Biomarker status: Biomarker testing is used to find out whether breast cancer cells have certain receptors.

Breast cancer tests

The following tests and procedures could also be used in the staging process:

Sentinel lymph node biopsy: The removal of the sentinel lymph node during surgery. The sentinel lymph node is the first lymph node in a group of lymph nodes to receive lymphatic drainage from the primary tumor. It is the first lymph node the cancer is likely to spread to from the primary tumor. A radioactive substance and/or blue dye is injected near the tumor, and the first lymph node to receive the substance or dye is removed. A pathologist examines the node.

Chest X-ray: Examines the organs and bones inside the chest. An X-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.

CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an X-ray machine. A dye is sometimes swallowed or injected into a vein to help the organs or tissues show up more clearly.

Bone scan: A procedure to check if there are rapidly dividing cells, such as cancer cells, in the bone. A very small amount of radioactive material is injected into a vein and travels through the bloodstream. The radioactive material collects in the bones with cancer and is detected by a scanner.

PET scan (positron emission tomography scan): A procedure to find malignant tumor cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.

Metastasis

Cancer can spread from where it began to other parts of the body. This is called metastasis.

There are three ways that cancer spreads in the body: through tissue, the lymph system and through the blood:

Tissue: The cancer spreads by growing into nearby areas.

Lymph system: The cancer spreads by getting into the lymph system. The cancer travels through the lymph vessels to other parts of the body.

Blood: The cancer spreads by getting into the blood. The cancer travels through the blood vessels to other parts of the body.

Lymph system: The cancer gets into the lymph system, travels through the lymph vessels, and forms a tumor (metastatic tumor) in another part of the body.

Blood: The cancer gets into the blood, travels through the blood vessels, and forms a tumor (metastatic tumor) in another part of the body.

The metastatic tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bone, the cancer cells in the bone are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.

Information from the National Breast Cancer Foundation. Learn more at www.nationalbreastcancer.org/about-breast-cancer/breast-cancer-staging.