In Breast Cancer, How Is Grading Different From Staging?

Getting a diagnosis of breast cancer can be scary and overwhelming. The stage of breast cancer will depend on the size and location of the tumor, where and how far it has spread, and what the cancer cells look like. It can be hard to understand what stage you’re at — and more importantly, what it might mean. Read on to learn more about the staging and grading of breast cancer, and what these might mean for your treatment options.

What does a breast cancer ‘stage’ refer to?

The stage of breast cancer helps describe how advanced the cancer is. Stage includes the tumor size, where it has spread in the body, specific markers on the tumor, and grade of tumor cells. 

The stages range from 0 to 4. The higher the number, the more advanced the cancer is. Knowing your cancer stage helps understand what treatment options you have. There are many factors that contribute to breast cancer staging, and it can be confusing, so be sure to talk with your doctor.

How is breast cancer stage determined?

Breast cancer staging will be determined by the combination of the following:

• TNM system: “T” describes the size of the tumor, “N” describes spread to lymph nodes, and “M” describes metastasis to other sites in the body.

• Receptor status: Breast cancer cells are tested for estrogen receptors (ER), progesterone receptors (PR), and hormone epidermal growth factor receptor 2 (HER2).

• Grade: Grade describes what the cancer cells look like when compared to normal cells. This correlates to how aggressive the cancer type is. 

What are the stages of breast cancer?

There are five stages of breast cancer, from Stage 0-4. Stage 0 is the earliest stage of breast cancer and means it has not spread. Stage 4 is the most advanced stage and means the breast cancer is invasive and has spread to other parts of the body. The stages can be further described as follows:

• Stage 0: The cancer is non-invasive, meaning the cancer is contained and has not spread beyond the original site.

• Stage 1: The cancer is in an early stage, and the cells have begun to spread into the surrounding area. There are subcategories of IA and IB based on tumor size, cancer spread, and receptor status.

• Stage 2: The cancer has spread more locally, increasing in size and/or spreading to lymph nodes. There are subcategories IIA and IIB based on tumor size, cancer spread, and receptor status.

• Stage 3: The cancer has advanced further to involve more lymph nodes or the chest wall or skin — but not to any other organs. This is sometimes called “regional spread.” There are three subcategories of IIIA, IIIB, IIIC. Inflammatory breast cancer is Stage IIIB or higher.

• Stage 4: This is when the cancer has spread (metastasized) beyond lymph nodes to other organs, such as the lung, brain, or bone.

What does it mean to ‘grade’ breast cancer?

The “grade” of breast cancer is a way to describe how the cancer cells look under a microscope. It helps to understand how aggressive it may be. If the tumor cells look very abnormal under the microscope, they’re more likely to grow quickly and spread. If the cells look very similar to normal cells, they’re likely to be more slow growing. 

To determine the grade, the following will be evaluated:

• How much the cells look like normal gland cells

• What the DNA-containing nucleus of the tumor cells look like

• The amount of dividing cells — a sign of how fast the cells are growing

What are the different grades of breast cancer?

Once the breast tumor is evaluated under a microscope, it will be given scores to determine the grade. There are three grades for breast cancer:

• Grade 1: This is a low-grade tumor. The tumor cells look similar to normal cells and will likely grow slowly.

• Grade 2: This is an intermediate-grade tumor. The tumor cells look a little different from normal cells.

• Grade 3: This is a high-grade tumor, meaning the cells look abnormal and are growing more quickly. 

The higher the grade, the more abnormal and aggressive the tumor is likely to be.

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Written by:

Christina Palmer, MD

Christina Palmer, MD, is a board-certified family physician with a special interest in chronic care management, women’s health, mental health, and preventive care. She has over 10 years of experience in primary care research, innovation, and practice.

Edited by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

Reviewed by:

Sophie Vergnaud, MD

Sophie Vergnaud, MD, is the Senior Medical Director for GoodRx Health. An experienced and dedicated pulmonologist and hospitalist, she spent a decade practicing and teaching clinical medicine at academic hospitals throughout London before transitioning to a career in health education and health technology.

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