Tumor Grade

Definition

Tumor grade refers to systems for determining the degree of malignancy of a tumor and classifies cells in terms of abnormal characteristics of the tumor cells (it is differentiated from cancer staging which refers to the severity and extent of the spread of the disease). It is determined by a pathologist from biopsied tumor tissue, as well as other characteristics of the tumor. The National Cancer Institute “Pathology Reports” (http://www.cancer.gov/about-cancer/diagnosis-staging/diagnosis/pathology-reports-fact-sheet) describes the information found in pathology reports.

Oncologists use a tumor grading system to help determine prognosis and treatment options. The specific characteristics differ in reference to different tumor types. Tumor types refer to the cells from which they developed (e.g., astrocytomas develop from unregulated growth of astrocytes). Other brain tumor types are not graded but classified by how abnormal the cancer cells and milieu looks and how likely...