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Definition |
The score derived from universally embraced prostate cancer grading system developed by Dr. Donald F. Gleason in 1977. The system provides a reproducible description of the glandular architecture of prostate tissue to which a pathologist assigns a score depending primarily on the microscopic patterns of cancerous glands and cell morphology. The system correlates well with behavior at the extremes: Gleason 1+1 tumors are the most well differentiated, slowly growing and rarely spread; Gleason 4+5 tumors are the most poorly differentiated, often widely metastatic at the time of diagnosis. In the commoner intermediate grade tumors, however, behavior is extremely variable.
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