Breast Cancer Classification Explained in Three Easy Paragraphs

A breast cancer diagnosis can feel overwhelming. You don’t even know which questions to ask! And all too often, appointments with a physician are a blur. So just in case you didn’t quite understand what your diagnosis means, we’ve got you covered. We’ve brought you this information on breast cancer classification. Seriously, we don’t know of a website where you will find a more succinct explanation than right here.

Physicians classify breast cancer by type, grade, and stage.

• • TYPE

     A biopsy reveals the type of breast cancer. One tumor may contain several types. The type depends upon the location and whether it is spreading. For example, a common type of breast cancer is DCIS. It stands for ductal (in the milk ducts) carcinoma (in the epithelial cells, which provide a covering or lining for the surfaces of organs and ducts) in situ (in place and not currently spreading).

• • GRADE

    Physicians usually use the Nottingham grading system to determine the grade of breast cancer. Using this system, pathologists assign a score of 1 to 3 to three features (gland formation, nuclear grade, and mitotic count). These are features of cancer cells seen under the microscope. A combined score of 3 to 5 is grade 1, in which cancer cells grow slowly and look slightly different than normal cells. A score of 6 or 7 is grade 2, which grows faster than grade 1 and looks different than normal cells. A score of 8 or 9 is grade 3. Grade 3 cancer grows quickly and looks much different than normal cells.

• • STAGE

    Several factors contribute to stage: size, whether the cancer has reached nearby lymph nodes, and whether it has spread to other parts of the body (metastasized). Stage ranges from 0 to IV and includes several substages. Cancer.org offers a detailed explanation of breast cancer stage, including a discussion of the TNM staging system. But in general, here are the stages:

    •  0 is small and within a duct or, in Paget’s disease of the nipple, without any underlying tumor.
    •  I is 2 cm or less with minimal spreading to a few axillary (underarm) lymph nodes.
    • II has spread to a few axillary lymph nodes but in a more substantial way or to internal mammary lymph nodes OR is larger than 2 cm OR is larger than 5 cm and has not spread to lymph nodes.
    • III is either less than 5 cm across but has spread to 4 to 9 axillary lymph nodes or has enlarged the internal mammary lymph nodes. Alternatively, it is larger than 5 cm and has spread to axillary or internal mammary lymph nodes, but hasn’t grown into the chest wall or skin.
    • IV is metastatic breast cancer. It has spread to lymph nodes or organs that are far from the breast and can be any size.

More Information

Some of our articles that are related to types of breast cancer: Mother/daughter breast cancer story (invasive breast cancer and DCIS), Sisters with breast cancer (stage II and stage III), Hope for patients with triple-negative breast cancer, Interview with stage IV survivor Karla Baptiste, Biomarkers for metastatic breast cancer that spreads to the brain.

If you’d like to know more about treatment for breast cancer, head over to our Breast Cancer Basics page and scroll down to the bottom. You’re welcome to join our private Facebook group for breast cancer patients and survivors, or sign up for our newsletter at the bottom of this page for more information and inspiration.