Tumor Grade (cont.)
In this Article
- What is a tumor?
- What is tumor grade?
- How is tumor grade determined?
- What do the different tumor grades signify?
- Does the same grading scale apply to all tumors?
- Does tumor grade affect a patient's treatment options?
- Tumor Grade At A Glance
- Find a local Doctor in your town
What is tumor grade?
Tumor grade is a system used to classify cancer cells in terms of how abnormal they look under a microscope and how quickly the tumor is likely to grow and spread. Many factors are considered when determining tumor grade, including the structure and growth pattern of the cells. The specific factors used to determine tumor grade vary with each type of cancer.
Histologic grade, also called differentiation, refers to how much the tumor cells resemble normal cells of the same tissue type. Nuclear grade refers to the size and shape of the nucleus in tumor cells and the percentage of tumor cells that are dividing.
Tumor grade should not be confused with the stage of a cancer. Cancer stage refers to the extent or severity of the cancer, based on factors such as the location of the primary tumor, tumor size, number of tumors, and lymph node involvement (spread of cancer into lymph nodes). (More information about staging is available in the NCI fact sheet Staging: Questions and Answers, which can be found at http://www.cancer.gov/cancertopics/factsheet/Detection/staging on the Internet.)
How is tumor grade determined?
If a tumor is suspected to be malignant, a doctor removes a sample of tissue or the entire tumor in a procedure called a biopsy. A pathologist (a doctor who identifies diseases by studying cells under a microscope) examines the tissue to determine whether the tumor is benign or malignant. The pathologist can also determine the tumor grade and identify other characteristics of the tumor cells.
What do the different tumor grades signify?
Based on the microscopic appearance of cancer cells, pathologists commonly describe tumor grade by four degrees of severity: Grades 1, 2, 3, and 4. The cells of Grade 1 tumors resemble normal cells, and tend to grow and multiply slowly. Grade 1 tumors are generally considered the least aggressive in behavior.
Conversely, the cells of Grade 3 or Grade 4 tumors do not look like normal cells of the same type. Grade 3 and 4 tumors tend to grow rapidly and spread faster than tumors with a lower grade.
|The American Joint Commission on Cancer recommends the following guidelines for grading tumors (1)|
|GX||Grade cannot be assessed (Undetermined grade)|
|G1||Well-differentiated (Low grade)|
|G2||Moderately differentiated (Intermediate grade)|
|G3||Poorly differentiated (High grade)|
|G4||Undifferentiated (High grade)|
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