Difference Between Grades and Stages of Breast Cancer

Breast cancer is assessed using two different systems: grading and staging. While both systems provide crucial information about the cancer, they focus on different aspects of the disease and have distinct purposes in diagnosis and treatment planning.

Grades of Breast Cancer

Grades refer to how much the cancer cells resemble normal cells. This is determined by examining the cancer cells under a microscope. The grade provides information about the cancer's likely growth rate and aggressiveness.

• Grade 1 (Low grade or Well-differentiated): Cancer cells look slightly different from normal cells and are usually slow-growing. They are well-organized and resemble normal cells closely.

• Grade 2 (Intermediate grade or Moderately differentiated): Cancer cells look more abnormal and grow faster than Grade 1 cells. They are less organized and have more variation in their appearance.

• Grade 3 (High grade or Poorly differentiated): Cancer cells look very different from normal cells and tend to grow and spread quickly. They are disorganized and have a high degree of variation in size and shape.

The grading system helps predict the aggressiveness of the cancer and guide treatment decisions. Higher-grade cancers are more likely to grow and spread quickly and may require more aggressive treatment (American Cancer Society, 2022).

Stages of Breast Cancer

Stages describe the extent to which cancer has spread within the body. The TNM system is often used to determine the stage of cancer, which includes:

• T (Tumor size): Size and extent of the main tumor.
• N (Nodes): Number of nearby lymph nodes that have cancer.
• M (Metastasis): Whether the cancer has spread to other parts of the body.

Based on the TNM results, breast cancer is classified into stages from 0 to IV:

• Stage 0: Non-invasive cancers (e.g., DCIS). The cancer cells are confined to their place of origin and have not spread.

• Stage I: Early-stage invasive cancer. The tumor is small and has not spread to lymph nodes or has minimal lymph node involvement.

• Stage II: The tumor is larger and/or has spread to a few nearby lymph nodes.

• Stage III: The cancer is more extensive but has not spread to distant sites. This stage includes larger tumors with more significant lymph node involvement or spread to nearby structures.

• Stage IV: The cancer has metastasized to other parts of the body, such as the bones, liver, or lungs. This is also known as metastatic breast cancer.

The staging system is essential for determining the prognosis and best course of treatment. Higher stages indicate more advanced disease and typically require more aggressive treatment (National Cancer Institute, 2021; Cancer Research UK, 2022).

Key Differences

1. Focus:

   • Grade: Concentrates on the microscopic appearance of cancer cells and their growth rate.
   • Stage: Focuses on the size of the tumor and the extent of its spread within the body.

2. Purpose:

   • Grade: Helps predict how quickly the cancer is likely to grow and spread.
   • Stage: Helps determine the prognosis and the most appropriate treatment options.

3. Measurement:

   • Grade: Assessed by a pathologist through microscopic examination of cancer cells.
   • Stage: Determined through physical exams, imaging tests, and biopsy results.

References

• American Cancer Society. (2022). Understanding Your Pathology Report: Breast Cancer. Retrieved from https://www.cancer.org/cancer/breast-cancer/understanding-a-breast-cancer-diagnosis/stages-of-breast-cancer.html
• National Cancer Institute. (2021). Cancer Staging. Retrieved from https://www.cancer.gov/about-cancer/diagnosis-staging/staging
• Cancer Research UK. (2022). Breast cancer stages, types and grades. Retrieved from https://www.cancerresearchuk.org/about-cancer/breast-cancer/stages-types-grades

Eryn Price RMT is the Founder of The Mastectomy Guide and provides accredited continuing education courses on integrative cancer care and post-surgical care for breast cancer, gender-affirmation and elective breast surgeries.  For a list of upcoming courses, please click here