Gleason score: all are true except:

Gleason score ranges from 2 to 10. Gleason score and grading system Gleason score is the most commonly used histological grading system for prostate cancer. The two most predominant histological patterns of the prostate cancer are assigned a Gleason grade ranging from 15. Primary grade is assigned to the pattern of cancer that is most commonly observed in the histological slides of the specimen. Secondary grade is assigned to the second most commonly observed pattern in the specimen. Gleason score is the sum of the two grades. Thus it is also known as Gleason sum. If the entire specimen has only one pattern present, then both the primary and sencondary grades are repoed as the same grade. As Gleason grades range from 1 to 5, Gleason score thus range from 2 to 10. The Gleason score is used to help evaluate the prognosis of men with prostate cancer. Together with other parameters, the Gleason score is incorporated into a strategy of prostate cancer staging which predicts prognosis and helps guide therapy. A point of impoance is that the primary Gleason grade is most impoant with respect to placing patients in prognostic groups. For example in patients with a Gleason score 7, a Gleason 4+3 is a more aggressive cancer than a Gleason 3+4. Ref : Smith's Urology 17/e p357