Understanding the Stages of Breast Cancer

The stages of breast cancer are listed in numerical order, 0 through IV, with each order signaling a more advanced stage of breast cancer. Knowing a patient’s stage helps the patient and doctor understand the prognosis, as well as talk about it with others. Each stage is based on four determining factors:

Although there are a few ways to classify the stage, the most widely used is the TNM system.

TNM stands for:

T = Tumor size

N = Lymph Node status (the number and location of lymph nodes with cancer)

M = Metastases (whether or not the cancer has spread to other areas of the body)

Stages of breast cancer

The stages of breast cancer range from 0 to IV (0 to 4).

Stage depends on the combination of tumor size (T), lymph node status (N) and metastases (M).

For example, a cancer with a T1 tumor (less than 2 cm), no lymph nodes with cancer (N0) and no metastases.

The highest stage (stage IV) is any cancer with metastases (M1), no matter the size of the tumor or the lymph node status.

Most often, the higher the stage of the cancer, the poorer the prognosis will be.

Below is a brief overview of the stages of breast cancer. Several stages have subcategories as well, but here we’re simply providing a general look at each stage.

Stage 0

Stage 0 breast cancer is noninvasive. In other words, there is no evidence of cancer cells or other abnormal cells invading neighboring tissue.

Stage I

In stage I breast cancer, the cancer is invasive. In other words, cancer cells or other abnormal cells are invading neighboring tissue. The tumor measures up to two centimeters long, but no lymph nodes are involved.

Stage II

Stage II breast cancer is also invasive. The tumor measures between two and five centimeters long, and the cancer may have spread to the lymph nodes under the arm.

Stage III

Stage III breast cancer, also known as locally advanced breast cancer, involves a tumor in the breast that is more than two inches long. The cancer has spread extensively into the lymph nodes or other tissue near the breast.

Stage IV

Stage IV breast cancer, also known as metastatic breast cancer (link to blog on metastatic breast cancer here?) is cancer that has spread from the breast into the lymph nodes, as well as other parts of the body near or far from the breast, including the bone, liver, and lungs.

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