Breast cancer cells are given a grade based on how much they look like normal cells when they are removed from the breast and checked in the lab. The grade is used to help predict the outcome (prognosis) and to figure out what treatments might work best. There are three grades of breast cancer: grade 1, grade 2, and grade 3.

• Grade 1: The cancer cells look similar to normal breast cells. These cancers tend to grow and spread slowly and have a good prognosis. This is also called low grade or well-differentiated breast cancer.

• Grade 2: The cells look quite different from normal breast cells. This means the features and prognosis are somewhere between well and poorly differentiated. This is also called intermediate grade or moderately differentiated breast cancer.

• Grade 3: The cells look very different from normal breast cells. They tend to grow and spread more quickly and have a worse prognosis. These are also called high grade or poorly differentiated breast cancer.

The grade of cancer is different from the cancer stage. A cancer’s grade is determined when a doctor (pathologist) looks at the cancer cells under a microscope, using tissue from a biopsy or after breast cancer surgery. If you have grade 3 breast cancer, youre more likely to be offered chemotherapy to help destroy any cancer cells that may have spread as a result of the cancer being faster growing. However, the grade of your cancer alone will not determine what treatment you’re offered. Your treatment team will consider the grade alongside all other information about your cancer.