Staging breast cancer helps doctors decide on treatment and estimate outcomes. A cancer stage is determined by the tumor’s size, where it is, the type of breast cancer, and whether it has spread.

Breast Cancer Stages

Stage 0
Noninvasive. Cancer cells are confined to the breast ducts and haven’t spread into nearby tissue.

Stage I
Cancer cells have moved into nearby breast tissue but remain small and localized.

Stage II
A tumor is present and may involve lymph nodes. Typical scenarios include:

• Tumor under 2 cm that has spread to underarm lymph nodes, or

• Tumor over 5 cm that hasn't reached the lymph nodes.
  Tumors between 2–5 cm may or may not involve nearby lymph nodes.

Stage III
Cancer has spread to nearby tissue and lymph nodes. This is often called “locally advanced” breast cancer.

Stage IV
Cancer has spread beyond the breast to other areas such as the liver, lungs, bones, or brain.

Treatment Options

Treatment depends on the stage and type of cancer. Most patients receive a combination of therapies. The five main approaches are:

Surgery – Removes the tumor and affected tissue.

Chemotherapy – Uses drugs (oral or IV) to shrink or destroy cancer cells.

Hormonal Therapy – Blocks hormones that certain cancers need to grow.

Biological Therapy – Supports the immune system in fighting cancer or managing treatment side effects.

Radiation Therapy – Uses targeted high-energy rays to kill cancer cells.

Some treatments focus only on the tumor area (local), while others work throughout the body (systemic).

Choosing a Treatment Plan

Your cancer doctor will help you understand which treatments are appropriate for your stage and type of breast cancer. They’ll walk you through the benefits, risks, and possible side effects.

For more detail, visit the National Cancer Institute’s Breast Cancer Treatment Option Overview, which also includes resources for finding care.