Understanding the stages and grades of breast cancer helps in determining the most appropriate treatment plan and predicting outcomes. Here’s an overview of the staging and grading systems:

Stages of Breast Cancer

The staging of breast cancer is determined using the TNM system, which considers the size of the tumor (T), whether cancer has spread to the lymph nodes (N), and whether it has metastasized to other parts of the body (M).

Stage 0

• Description: Non-invasive or in situ cancer. This includes ductal carcinoma in situ (DCIS) where the cancer cells are confined to the ducts and have not spread to surrounding tissues.
• Sources: American Cancer Society, National Cancer Institute

Stage I

• Stage IA: The tumor is 2 cm or smaller and has not spread outside the breast.
• Stage IB: Small clusters of cancer cells are found in lymph nodes, and either no tumor is found in the breast or the tumor is 2 cm or smaller.
• Sources: American Cancer Society, Mayo Clinic

Stage II

• Stage IIA: No tumor is found in the breast, but cancer is found in 1 to 3 axillary lymph nodes or in the lymph nodes near the breastbone; or the tumor is 2 to 5 cm and has not spread to the lymph nodes.
• Stage IIB: The tumor is 2 to 5 cm and has spread to 1 to 3 axillary lymph nodes or lymph nodes near the breastbone; or the tumor is larger than 5 cm but has not spread to the lymph nodes.
• Sources: National Cancer Institute, BreastCancer.org

Stage III

• Stage IIIA: The tumor is larger than 5 cm and has spread to 1 to 3 axillary lymph nodes or any lymph nodes near the breastbone; or the tumor is smaller than 5 cm but has spread to 4 to 9 axillary lymph nodes or the lymph nodes near the breastbone.
• Stage IIIB: The tumor has spread to the chest wall or skin and may have spread to up to 9 lymph nodes.
• Stage IIIC: Cancer has spread to 10 or more axillary lymph nodes, lymph nodes above or below the collarbone, or internal mammary lymph nodes.
• Sources: American Cancer Society, Mayo Clinic

Stage IV

• Description: Metastatic breast cancer, where cancer has spread beyond the breast and nearby lymph nodes to other parts of the body such as bones, liver, lungs, or brain.
• Sources: National Cancer Institute, BreastCancer.org

Grades of Breast Cancer

The grade of breast cancer refers to how much the cancer cells resemble normal cells. This is determined by examining the cancer cells under a microscope.

Grade 1 (Low Grade)

• Description: The cancer cells look more like normal cells and tend to grow and spread more slowly.
• Sources: American Cancer Society, National Cancer Institute

Grade 2 (Intermediate Grade)

• Description: The cancer cells are moderately differentiated, meaning they do not look like normal cells and grow at a faster rate than grade 1 cancer cells.
• Sources: BreastCancer.org, Mayo Clinic

Grade 3 (High Grade)

• Description: The cancer cells look very different from normal cells and tend to grow and spread more aggressively.
• Sources: American Cancer Society, National Cancer Institute

Summary

Understanding the stage and grade of breast cancer helps in predicting the likely course of the disease and choosing the most appropriate treatment. Stages range from 0 to IV, indicating the extent of cancer spread, while grades range from 1 to 3, indicating how abnormal the cells look and how quickly they are likely to grow and spread.

Additional Resources

• American Cancer Society: Stages of Breast Cancer
• National Cancer Institute: Breast Cancer Treatment (PDQ®)–Patient Version
• BreastCancer.org: Staging and Grading

By understanding the stages and grades of breast cancer, patients and healthcare providers can work together to develop a tailored treatment plan that addresses the specific characteristics of the cancer.