Understanding Prostate Cancer Tumor Grades: Gleason Scoring Explained

The grade of a prostate tumor refers to a scoring system named after a physician, Donald Gleason. The grade is a combination of two category numbers---the primary grade and the second most common grade. Each number can range from one to five. The higher the total grade, the more dangerous the cancer is.

Grading Categories

• The primary grade cells must make up at least 51 percent of the total microscopic picture. The secondary grade has to be between 5 and 49 percent of what the pathologist sees.

Grades 2 to 4

• These are low-grade tumors with well-differentiated cells resembling normal prostate cells. These grades are much less commonly seen than more advanced stages. There can be some spreading into the prostate muscle.

Grades 5 to 7

• Grade 6 is the most common finding after biopsy. Typically, this is a combination of a Grade 3 for both primary and secondary category. In each case, they represent intermediate-grade tumors, which may or may not develop further.

Grades 8 to 10

• These grades consist of poorly differentiated tumor cells in the high-grade cancer category. These cancers are very aggressive and difficult to treat successfully.

Warning

• Reading Gleason grades accurately is a task for pathologists who specialize in this area. If a less experienced doctor assigns a higher or lower score, the patient may be overtreated or undertreated for the condition.