What are some of the cancer type-specific grading systems?
Breast and prostate cancers are the most common types of cancer that have their own grading systems.
Breast cancer. Doctors most often use the Nottingham grading system (also called the Elston-Ellis modification of the Scarff-Bloom-Richardson grading system) for breast cancer (1). This system grades breast tumors based on the following features:
- Tubule formation: how much of the tumor tissue has normal breast (milk) duct structures
- Nuclear grade: an evaluation of the size and shape of the nucleus in the tumor cells
- Mitotic rate: how many dividing cells are present, which is a measure of how fast the tumor cells are growing and dividing
Each of the categories gets a score between 1 and 3; a score of “1” means the cells and tumor tissue look the most like normal cells and tissue, and a score of “3” means the cells and tissue look the most abnormal. The scores for the three categories are then added, yielding a total score of 3 to 9. Three grades are possible:
- Total score = 3–5: G1 (Low grade or well differentiated)
- Total score = 6–7: G2 (Intermediate grade or moderately differentiated)
- Total score = 8–9: G3 (High grade or poorly differentiated)
Prostate cancer. The Gleason scoring system is used to grade prostate cancer (1). The Gleason score is based on biopsy samples taken from the prostate. The pathologist checks the samples to see how similar the tumor tissue looks to normal prostate tissue. Both a primary and a secondary pattern of tissue organization are identified. The primary pattern represents the most common tissue pattern seen in the tumor, and the secondary pattern represents the next most common pattern. Each pattern is given a grade from 1 to 5, with 1 looking the most like normal prostate tissue and 5 looking the most abnormal. The two grades are then added to give a Gleason score. The American Joint Committee on Cancer recommends grouping Gleason scores into the following categories (1):
- Gleason X: Gleason score cannot be determined
- Gleason 2–6: The tumor tissue is well differentiated
- Gleason 7: The tumor tissue is moderately differentiated
- Gleason 8–10: The tumor tissue is poorly differentiated or undifferentiated
How does tumor grade affect a patient’s treatment options?
Doctors use tumor grade and other factors, such as cancer stage and a patient’s age and general health, to develop a treatment plan and to determine a patient’s prognosis (the likely outcome or course of a disease; the chance of recovery or recurrence). Generally, a lower grade indicates a better prognosis. A higher-grade cancer may grow and spread more quickly and may require immediate or more aggressive treatment.
The importance of tumor grade in planning treatment and determining a patient’s prognosis is greater for certain types of cancer, such as soft tissue sarcoma, primary brain tumors, and breast and prostate cancer.
Patients should talk with their doctor for more information about tumor grade and how it relates to their treatment and prognosis.
1. American Joint Committee on Cancer. AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer; 2010.
Source: National Cancer Institute.