A tumor’s histologic grade describes how abnormal the cancer cells and tissue look under a microscope, and how likely the cancer cells are to grow and spread.
TUMOR GRADE CONVERSION LIST
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GX: The grade cannot be evaluated
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GB: The tissue is considered borderline cancerous
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G1: The tissue is well-differentiated (contains many healthy-looking cells) – (Low)
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G2: The tissue is moderately differentiated (more cells appear abnormal than healthy) – (Intermediate)
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G3: The tissue is poorly differentiated (most cells appear abnormal) – (High)
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G3 to G4: The tissue is undifferentiated (all cells appear abnormal) – (High)
Clear cell, mixed mullerian (carcinosarcomas) and all high grade histologies, are considered tumor grade “ G3-poorly differentiated”
A borderline histologic grade, or GB: Grade Borderline (“B”), is a tumor grade assigned when a tumor is considered borderline cancerous.
If a pathology report refers to the histologic grade as a range, for example “moderately to poorly differentiated”, choose the highest grade reported (“poorly differentiated”-G3).