Hormone receptor status and HER2 status are tumor characteristics or biomarkers used to determine if hormone therapy and HER2-targeted therapies should be included in your treatment plan. Hormone receptor status tells doctors whether breast cancer cells use hormones like estrogen or progesterone to divide and grow.

HER2 status shows them whether the cells have too much of a surface protein called HER2 that can help breast cancer cells divide and grow. Tumor grade is a way of classifying tumors based on the appearance of the cancer cells and how quickly they’re growing. The more abnormal and fast-growing the cancer cells appear, the higher the tumor grade.

Breast cancer stage describes how much cancer is in the body. It’s the most important factor in prognosis. Staging looks at the size of the tumor, the number and location of cancerous lymph nodes, and whether the cancer has spread to other tissue or organs. It also looks at tumor characteristics. All of this information helps guide treatment decisions.

The spread of cancer is described in stages 0 to 4 based in part on whether the cancer is confined to the breast or has spread to other parts of the body. Stage 0 breast cancer is ductal carcinoma in situ, or DCIS. With DCIS, the abnormal cells are contained in the milk ducts of the breast and have not invaded nearby tissue outside the milk ducts. Stage 1 breast cancer is often referred to as local or confined within the breast. Even if cancer is found in several places in the breast, it’s still considered local. In stages 2 and 3, breast cancer may have spread to the lymph nodes, mainly to the axillary lymph nodes in the underarm area.

In stage 4, breast cancer has spread to other parts of the body and is described as distant, which is another term for metastatic breast cancer.

The most common method of staging breast cancer is called the TNM system. This system looks at the size of the tumor (T), the lymph node status (N), and metastasis (M). In the past, tumor stage was based only on with these 3 measurements. Starting in 2018, more measures were added to TNM system staging, including:

• Tumor grade
• Estrogen receptor status
• Progesterone receptor status, and
• HER2 status

These factors are combined to assign a breast cancer stage, ranging from 0 to 4. In general, the lower the stage, the better the prognosis. The Oncotype DX® test may be used as part of breast cancer staging for some estrogen receptor-positive, lymph node-negative tumors. It’s the only tumor profiling test used in breast cancer staging today. Staging can be complex and hard to understand. Most people will benefit from a discussion detailing their staging results with their doctor. For more information on factors that affect prognosis and treatment, visit the Diagnosis section on komen.org.